diff --git a/package.json b/package.json
index 0cc32eb9eb..5c2ce7c6c8 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "graphql",
-  "version": "14.5.1",
+  "version": "14.5.2",
   "description": "A Query Language and Runtime which can target any service.",
   "license": "MIT",
   "private": true,
diff --git a/src/type/definition.js b/src/type/definition.js
index b52f87c72f..3fe9920246 100644
--- a/src/type/definition.js
+++ b/src/type/definition.js
@@ -791,6 +791,7 @@ function defineFieldMap<TSource, TContext>(
     }));
 
     return {
+      ...fieldConfig,
       name: fieldName,
       description: fieldConfig.description,
       type: fieldConfig.type,
@@ -1423,6 +1424,7 @@ function defineInputFieldMap(
     );
 
     return {
+      ...fieldConfig,
       name: fieldName,
       description: fieldConfig.description,
       type: fieldConfig.type,
diff --git a/src/version.js b/src/version.js
index 1c2451a647..c486590536 100644
--- a/src/version.js
+++ b/src/version.js
@@ -8,7 +8,7 @@
 /**
  * A string containing the version of the GraphQL.js library
  */
-export const version = '14.5.1';
+export const version = '14.5.2';
 
 /**
  * An object containing the components of the GraphQL.js version string
@@ -16,6 +16,6 @@ export const version = '14.5.1';
 export const versionInfo = Object.freeze({
   major: 14,
   minor: 5,
-  patch: 1,
+  patch: 2,
   preReleaseTag: null,
 });
diff --git a/tstypes/graphql.d.ts b/tstypes/graphql.d.ts
index a1c43c0d5f..90b29c9c4d 100644
--- a/tstypes/graphql.d.ts
+++ b/tstypes/graphql.d.ts
@@ -1,7 +1,7 @@
 import Maybe from './tsutils/Maybe';
 import { Source } from './language/source';
-import { GraphQLFieldResolver } from './type/definition';
 import { GraphQLSchema } from './type/schema';
+import { GraphQLFieldResolver, GraphQLTypeResolver } from './type/definition';
 import {
   ExecutionResult,
   ExecutionResultDataDefault,
@@ -44,12 +44,13 @@ import {
  */
 export interface GraphQLArgs {
   schema: GraphQLSchema;
-  source: Source | string;
+  source: string | Source;
   rootValue?: any;
   contextValue?: any;
   variableValues?: Maybe<{ [key: string]: any }>;
   operationName?: Maybe<string>;
   fieldResolver?: Maybe<GraphQLFieldResolver<any, any>>;
+  typeResolver?: Maybe<GraphQLTypeResolver<any, any>>;
 }
 
 export function graphql<TData = ExecutionResultDataDefault>(
@@ -63,6 +64,7 @@ export function graphql<TData = ExecutionResultDataDefault>(
   variableValues?: Maybe<{ [key: string]: any }>,
   operationName?: Maybe<string>,
   fieldResolver?: Maybe<GraphQLFieldResolver<any, any>>,
+  typeResolver?: Maybe<GraphQLTypeResolver<any, any>>,
 ): Promise<ExecutionResult<TData>>;
 
 /**
@@ -82,4 +84,5 @@ export function graphqlSync<TData = ExecutionResultDataDefault>(
   variableValues?: Maybe<{ [key: string]: any }>,
   operationName?: Maybe<string>,
   fieldResolver?: Maybe<GraphQLFieldResolver<any, any>>,
+  typeResolver?: Maybe<GraphQLTypeResolver<any, any>>,
 ): ExecutionResult<TData>;
diff --git a/tstypes/index.d.ts b/tstypes/index.d.ts
index f9a5acbdd7..942cc2e918 100644
--- a/tstypes/index.d.ts
+++ b/tstypes/index.d.ts
@@ -1,12 +1,40 @@
 // TypeScript Version: 2.6
 
+/**
+ * GraphQL.js provides a reference implementation for the GraphQL specification
+ * but is also a useful utility for operating on GraphQL files and building
+ * sophisticated tools.
+ *
+ * This primary module exports a general purpose function for fulfilling all
+ * steps of the GraphQL specification in a single operation, but also includes
+ * utilities for every part of the GraphQL specification:
+ *
+ *   - Parsing the GraphQL language.
+ *   - Building a GraphQL type schema.
+ *   - Validating a GraphQL request against a type schema.
+ *   - Executing a GraphQL request against a type schema.
+ *
+ * This also includes utility functions for operating on GraphQL types and
+ * GraphQL documents to facilitate building tools.
+ *
+ * You may also import from each sub-directory directly. For example, the
+ * following two import statements are equivalent:
+ *
+ *     import { parse } from 'graphql';
+ *     import { parse } from 'graphql/language';
+ */
+
+// The GraphQL.js version info.
+export { version, versionInfo } from './version';
+
 // The primary entry point into fulfilling a GraphQL request.
-export { graphql, graphqlSync, GraphQLArgs } from './graphql';
+export { GraphQLArgs, graphql, graphqlSync } from './graphql';
 
 // Create and operate on GraphQL type definitions and schema.
 export {
-  GraphQLSchema,
   // Definitions
+  GraphQLSchema,
+  GraphQLDirective,
   GraphQLScalarType,
   GraphQLObjectType,
   GraphQLInterfaceType,
@@ -15,10 +43,7 @@ export {
   GraphQLInputObjectType,
   GraphQLList,
   GraphQLNonNull,
-  GraphQLDirective,
-  // "Enum" of Type Kinds
-  TypeKind,
-  // Scalars
+  // Standard GraphQL Scalars
   specifiedScalarTypes,
   GraphQLInt,
   GraphQLFloat,
@@ -30,12 +55,10 @@ export {
   GraphQLIncludeDirective,
   GraphQLSkipDirective,
   GraphQLDeprecatedDirective,
+  // "Enum" of Type Kinds
+  TypeKind,
   // Constant Deprecation Reason
   DEFAULT_DEPRECATION_REASON,
-  // Meta-field definitions.
-  SchemaMetaFieldDef,
-  TypeMetaFieldDef,
-  TypeNameMetaFieldDef,
   // GraphQL Types for introspection.
   introspectionTypes,
   __Schema,
@@ -46,6 +69,10 @@ export {
   __InputValue,
   __EnumValue,
   __TypeKind,
+  // Meta-field definitions.
+  SchemaMetaFieldDef,
+  TypeMetaFieldDef,
+  TypeNameMetaFieldDef,
   // Predicates
   isSchema,
   isDirective,
@@ -72,6 +99,8 @@ export {
   isIntrospectionType,
   isSpecifiedDirective,
   // Assertions
+  assertSchema,
+  assertDirective,
   assertType,
   assertScalarType,
   assertObjectType,
@@ -95,7 +124,9 @@ export {
   // Validate GraphQL schema.
   validateSchema,
   assertValidSchema,
-  // type
+} from './type';
+
+export {
   GraphQLType,
   GraphQLInputType,
   GraphQLOutputType,
@@ -107,6 +138,7 @@ export {
   GraphQLNamedType,
   Thunk,
   GraphQLSchemaConfig,
+  GraphQLDirectiveConfig,
   GraphQLArgument,
   GraphQLArgumentConfig,
   GraphQLEnumTypeConfig,
@@ -132,7 +164,6 @@ export {
   GraphQLScalarTypeConfig,
   GraphQLTypeResolver,
   GraphQLUnionTypeConfig,
-  GraphQLDirectiveConfig,
   GraphQLScalarSerializer,
   GraphQLScalarValueParser,
   GraphQLScalarLiteralParser,
@@ -142,6 +173,12 @@ export {
 export {
   Source,
   getLocation,
+  // Print source location
+  printLocation,
+  printSourceLocation,
+  // Lex
+  createLexer,
+  TokenKind,
   // Parse
   parse,
   parseValue,
@@ -153,10 +190,9 @@ export {
   visitInParallel,
   visitWithTypeInfo,
   getVisitFn,
+  BREAK,
   Kind,
-  TokenKind,
   DirectiveLocation,
-  BREAK,
   // Predicates
   isDefinitionNode,
   isExecutableDefinitionNode,
@@ -167,20 +203,26 @@ export {
   isTypeDefinitionNode,
   isTypeSystemExtensionNode,
   isTypeExtensionNode,
-  // type
+} from './language';
+
+export {
   Lexer,
   ParseOptions,
   SourceLocation,
+  Location,
+  Token,
+  TokenKindEnum,
+  KindEnum,
+  DirectiveLocationEnum,
   // Visitor utilities
   ASTVisitor,
   Visitor,
   VisitFn,
   VisitorKeyMap,
   // AST nodes
-  Location,
-  Token,
   ASTNode,
   ASTKindToNode,
+  // Each kind of AST node
   NameNode,
   DocumentNode,
   DefinitionNode,
@@ -234,25 +276,26 @@ export {
   UnionTypeExtensionNode,
   EnumTypeExtensionNode,
   InputObjectTypeExtensionNode,
-  KindEnum,
-  TokenKindEnum,
-  DirectiveLocationEnum,
 } from './language';
 
 // Execute GraphQL queries.
 export {
   execute,
   defaultFieldResolver,
+  defaultTypeResolver,
   responsePathAsArray,
   getDirectiveValues,
-  // type
   ExecutionArgs,
   ExecutionResult,
 } from './execution';
 
-export { subscribe, createSourceEventStream } from './subscription';
+export {
+  subscribe,
+  createSourceEventStream,
+  SubscriptionArgs,
+} from './subscription';
 
-// Validate GraphQL queries.
+// Validate GraphQL documents.
 export {
   validate,
   ValidationContext,
@@ -284,13 +327,16 @@ export {
   ValuesOfCorrectTypeRule,
   VariablesAreInputTypesRule,
   VariablesInAllowedPositionRule,
+  ValidationRule,
 } from './validation';
 
-// Create and format GraphQL errors.
+// Create, format, and print GraphQL errors.
 export {
   GraphQLError,
-  formatError,
+  syntaxError,
+  locatedError,
   printError,
+  formatError,
   GraphQLFormattedError,
 } from './error';
 
@@ -299,13 +345,13 @@ export {
   // Produce the GraphQL query recommended for a full schema introspection.
   // Accepts optional IntrospectionOptions.
   getIntrospectionQuery,
-  // @deprecated: use getIntrospectionQuery - will be removed in v15
+  // @deprecated: use getIntrospectionQuery - will be removed in v15.
   introspectionQuery,
-  // Gets the target Operation from a Document
+  // Gets the target Operation from a Document.
   getOperationAST,
   // Gets the Type for the target Operation AST.
   getOperationRootType,
-  // Convert a GraphQLSchema to an IntrospectionQuery
+  // Convert a GraphQLSchema to an IntrospectionQuery.
   introspectionFromSchema,
   // Build a GraphQLSchema from an introspection result.
   buildClientSchema,
@@ -314,7 +360,7 @@ export {
   // Build a GraphQLSchema from a GraphQL schema language document.
   buildSchema,
   // @deprecated: Get the description from a schema AST node and supports legacy
-  // syntax for specifying descriptions - will be removed in v16
+  // syntax for specifying descriptions - will be removed in v16.
   getDescription,
   // Extends an existing GraphQLSchema from a parsed GraphQL Schema
   // language AST.
@@ -323,11 +369,11 @@ export {
   lexicographicSortSchema,
   // Print a GraphQLSchema to GraphQL Schema language.
   printSchema,
+  // Print a GraphQLType to GraphQL Schema language.
+  printType,
   // Prints the built-in introspection schema in the Schema Language
   // format.
   printIntrospectionSchema,
-  // Print a GraphQLType to GraphQL Schema language.
-  printType,
   // Create a GraphQLType from a GraphQL language AST.
   typeFromAST,
   // Create a JavaScript value from a GraphQL language AST with a Type.
@@ -340,8 +386,10 @@ export {
   // the GraphQL type system.
   TypeInfo,
   // Coerces a JavaScript value to a GraphQL type, or produces errors.
+  coerceInputValue,
+  // @deprecated use coerceInputValue - will be removed in v15
   coerceValue,
-  // @deprecated use coerceValue - will be removed in v15
+  // @deprecated use coerceInputValue - will be removed in v15
   isValidJSValue,
   // @deprecated use validation - will be removed in v15
   isValidLiteralValue,
@@ -349,6 +397,9 @@ export {
   concatAST,
   // Separates an AST into an AST per Operation.
   separateOperations,
+  // Strips characters that are not significant to the validity or execution
+  // of a GraphQL document.
+  stripIgnoredCharacters,
   // Comparators for types
   isEqualType,
   isTypeSubTypeOf,
@@ -358,36 +409,38 @@ export {
   // Determine if a string is a valid GraphQL name.
   isValidNameError,
   // Compares two GraphQLSchemas and detects breaking changes.
-  findBreakingChanges,
-  findDangerousChanges,
   BreakingChangeType,
   DangerousChangeType,
+  findBreakingChanges,
+  findDangerousChanges,
   // Report all deprecated usage within a GraphQL document.
   findDeprecatedUsages,
-  // type
-  BuildSchemaOptions,
-  BreakingChange,
-  DangerousChange,
+} from './utilities';
+
+export {
   IntrospectionOptions,
-  IntrospectionDirective,
+  IntrospectionQuery,
+  IntrospectionSchema,
+  IntrospectionType,
+  IntrospectionInputType,
+  IntrospectionOutputType,
+  IntrospectionScalarType,
+  IntrospectionObjectType,
+  IntrospectionInterfaceType,
+  IntrospectionUnionType,
   IntrospectionEnumType,
-  IntrospectionEnumValue,
-  IntrospectionField,
   IntrospectionInputObjectType,
-  IntrospectionInputType,
+  IntrospectionTypeRef,
   IntrospectionInputTypeRef,
-  IntrospectionInputValue,
-  IntrospectionInterfaceType,
-  IntrospectionListTypeRef,
+  IntrospectionOutputTypeRef,
   IntrospectionNamedTypeRef,
+  IntrospectionListTypeRef,
   IntrospectionNonNullTypeRef,
-  IntrospectionObjectType,
-  IntrospectionOutputType,
-  IntrospectionOutputTypeRef,
-  IntrospectionQuery,
-  IntrospectionScalarType,
-  IntrospectionSchema,
-  IntrospectionType,
-  IntrospectionTypeRef,
-  IntrospectionUnionType,
+  IntrospectionField,
+  IntrospectionInputValue,
+  IntrospectionEnumValue,
+  IntrospectionDirective,
+  BuildSchemaOptions,
+  BreakingChange,
+  DangerousChange,
 } from './utilities';
diff --git a/tstypes/language/index.d.ts b/tstypes/language/index.d.ts
index e15060e7f2..7cd95901c9 100644
--- a/tstypes/language/index.d.ts
+++ b/tstypes/language/index.d.ts
@@ -1,5 +1,8 @@
 export { Source } from './source';
 export { getLocation, SourceLocation } from './location';
+
+export { printLocation, printSourceLocation } from './printLocation';
+
 export { Kind, KindEnum } from './kinds';
 export { TokenKind, TokenKindEnum } from './tokenKind';
 export { createLexer, Lexer } from './lexer';
diff --git a/tstypes/type/definition.d.ts b/tstypes/type/definition.d.ts
index 28b68dd7ac..b468797748 100644
--- a/tstypes/type/definition.d.ts
+++ b/tstypes/type/definition.d.ts
@@ -1,5 +1,6 @@
 import Maybe from '../tsutils/Maybe';
 import { PromiseOrValue } from '../jsutils/PromiseOrValue';
+import { Path } from '../jsutils/Path';
 import {
   ScalarTypeDefinitionNode,
   ObjectTypeDefinitionNode,
@@ -75,6 +76,7 @@ export function assertNonNullType(type: any): GraphQLNonNull<any>;
 /**
  * These types may be used as input types for arguments and directives.
  */
+// TS_SPECIFIC: TS does not allow recursive type definitions, hence the `any`s
 export type GraphQLInputType =
   | GraphQLScalarType
   | GraphQLEnumType
@@ -94,6 +96,7 @@ export function assertInputType(type: any): GraphQLInputType;
 /**
  * These types may be used as output types as the result of fields.
  */
+// TS_SPECIFIC: TS does not allow recursive type definitions, hence the `any`s
 export type GraphQLOutputType =
   | GraphQLScalarType
   | GraphQLObjectType
@@ -285,13 +288,16 @@ export class GraphQLScalarType {
   serialize: GraphQLScalarSerializer<any>;
   parseValue: GraphQLScalarValueParser<any>;
   parseLiteral: GraphQLScalarLiteralParser<any>;
+  extensions: Maybe<Readonly<Record<string, any>>>;
   astNode: Maybe<ScalarTypeDefinitionNode>;
   extensionASTNodes: Maybe<ReadonlyArray<ScalarTypeExtensionNode>>;
   constructor(config: GraphQLScalarTypeConfig<any, any>);
 
   toConfig(): GraphQLScalarTypeConfig<any, any> & {
+    serialize: GraphQLScalarSerializer<any>;
     parseValue: GraphQLScalarValueParser<any>;
     parseLiteral: GraphQLScalarLiteralParser<any>;
+    extensions: Maybe<Readonly<Record<string, any>>>;
     extensionASTNodes: ReadonlyArray<ScalarTypeExtensionNode>;
   };
 
@@ -320,6 +326,7 @@ export interface GraphQLScalarTypeConfig<TInternal, TExternal> {
   parseValue?: GraphQLScalarValueParser<TInternal>;
   // Parses an externally provided literal value to use as an input.
   parseLiteral?: GraphQLScalarLiteralParser<TInternal>;
+  extensions?: Maybe<Readonly<Record<string, any>>>;
   astNode?: Maybe<ScalarTypeDefinitionNode>;
   extensionASTNodes?: Maybe<ReadonlyArray<ScalarTypeExtensionNode>>;
 }
@@ -368,9 +375,10 @@ export class GraphQLObjectType<
 > {
   name: string;
   description: Maybe<string>;
+  isTypeOf: Maybe<GraphQLIsTypeOfFn<TSource, TContext>>;
+  extensions: Maybe<Readonly<Record<string, any>>>;
   astNode: Maybe<ObjectTypeDefinitionNode>;
   extensionASTNodes: Maybe<ReadonlyArray<ObjectTypeExtensionNode>>;
-  isTypeOf: Maybe<GraphQLIsTypeOfFn<TSource, TContext>>;
 
   constructor(config: GraphQLObjectTypeConfig<TSource, TContext, TArgs>);
   getFields(): GraphQLFieldMap<any, TContext, TArgs>;
@@ -387,20 +395,27 @@ export class GraphQLObjectType<
   inspect(): string;
 }
 
+export function argsToArgsConfig(
+  args: ReadonlyArray<GraphQLArgument>,
+): GraphQLFieldConfigArgumentMap;
+
+// TS_SPECIFIC: TArgs
 export interface GraphQLObjectTypeConfig<
   TSource,
   TContext,
   TArgs = { [key: string]: any }
 > {
   name: string;
+  description?: Maybe<string>;
   interfaces?: Thunk<Maybe<GraphQLInterfaceType[]>>;
   fields: Thunk<GraphQLFieldConfigMap<TSource, TContext, TArgs>>;
   isTypeOf?: Maybe<GraphQLIsTypeOfFn<TSource, TContext>>;
-  description?: Maybe<string>;
+  extensions?: Maybe<Readonly<Record<string, any>>>;
   astNode?: Maybe<ObjectTypeDefinitionNode>;
   extensionASTNodes?: Maybe<ReadonlyArray<ObjectTypeExtensionNode>>;
 }
 
+// TS_SPECIFIC: TArgs
 export type GraphQLTypeResolver<
   TSource,
   TContext,
@@ -435,7 +450,7 @@ export interface GraphQLResolveInfo {
   readonly fieldNodes: ReadonlyArray<FieldNode>;
   readonly returnType: GraphQLOutputType;
   readonly parentType: GraphQLObjectType;
-  readonly path: ResponsePath;
+  readonly path: Path;
   readonly schema: GraphQLSchema;
   readonly fragments: { [key: string]: FragmentDefinitionNode };
   readonly rootValue: any;
@@ -443,22 +458,18 @@ export interface GraphQLResolveInfo {
   readonly variableValues: { [variableName: string]: any };
 }
 
-export type ResponsePath = {
-  readonly prev: ResponsePath | undefined;
-  readonly key: string | number;
-};
-
 export interface GraphQLFieldConfig<
   TSource,
   TContext,
   TArgs = { [argName: string]: any }
 > {
+  description?: Maybe<string>;
   type: GraphQLOutputType;
   args?: GraphQLFieldConfigArgumentMap;
   resolve?: GraphQLFieldResolver<TSource, TContext, TArgs>;
   subscribe?: GraphQLFieldResolver<TSource, TContext, TArgs>;
   deprecationReason?: Maybe<string>;
-  description?: Maybe<string>;
+  extensions?: Maybe<Readonly<Record<string, any>>>;
   astNode?: Maybe<FieldDefinitionNode>;
 }
 
@@ -467,12 +478,14 @@ export type GraphQLFieldConfigArgumentMap = {
 };
 
 export interface GraphQLArgumentConfig {
+  description?: Maybe<string>;
   type: GraphQLInputType;
   defaultValue?: any;
-  description?: Maybe<string>;
+  extensions?: Maybe<Readonly<Record<string, any>>>;
   astNode?: Maybe<InputValueDefinitionNode>;
 }
 
+// TS_SPECIFIC: TArgs
 export type GraphQLFieldConfigMap<
   TSource,
   TContext,
@@ -494,19 +507,22 @@ export interface GraphQLField<
   subscribe?: GraphQLFieldResolver<TSource, TContext, TArgs>;
   isDeprecated?: boolean;
   deprecationReason?: Maybe<string>;
+  extensions: Maybe<Readonly<Record<string, any>>>;
   astNode?: Maybe<FieldDefinitionNode>;
 }
 
 export interface GraphQLArgument {
   name: string;
+  description: Maybe<string>;
   type: GraphQLInputType;
-  defaultValue?: any;
-  description?: Maybe<string>;
-  astNode?: Maybe<InputValueDefinitionNode>;
+  defaultValue: any;
+  extensions: Maybe<Readonly<Record<string, any>>>;
+  astNode: Maybe<InputValueDefinitionNode>;
 }
 
 export function isRequiredArgument(arg: GraphQLArgument): boolean;
 
+// TS_SPECIFIC: TArgs
 export type GraphQLFieldMap<
   TSource,
   TContext,
@@ -536,9 +552,10 @@ export type GraphQLFieldMap<
 export class GraphQLInterfaceType {
   name: string;
   description: Maybe<string>;
+  resolveType: Maybe<GraphQLTypeResolver<any, any>>;
+  extensions: Maybe<Readonly<Record<string, any>>>;
   astNode?: Maybe<InterfaceTypeDefinitionNode>;
   extensionASTNodes: Maybe<ReadonlyArray<InterfaceTypeExtensionNode>>;
-  resolveType: Maybe<GraphQLTypeResolver<any, any>>;
 
   constructor(config: GraphQLInterfaceTypeConfig<any, any>);
 
@@ -546,6 +563,7 @@ export class GraphQLInterfaceType {
 
   toConfig(): GraphQLInterfaceTypeConfig<any, any> & {
     fields: GraphQLFieldConfigMap<any, any>;
+    extensions: Maybe<Readonly<Record<string, any>>>;
     extensionASTNodes: ReadonlyArray<InterfaceTypeExtensionNode>;
   };
 
@@ -554,12 +572,14 @@ export class GraphQLInterfaceType {
   inspect(): string;
 }
 
+// TS_SPECIFIC: TArgs
 export interface GraphQLInterfaceTypeConfig<
   TSource,
   TContext,
   TArgs = { [key: string]: any }
 > {
   name: string;
+  description?: Maybe<string>;
   fields: Thunk<GraphQLFieldConfigMap<TSource, TContext, TArgs>>;
   /**
    * Optionally provide a custom type resolver function. If one is not provided,
@@ -567,7 +587,7 @@ export interface GraphQLInterfaceTypeConfig<
    * Object type.
    */
   resolveType?: Maybe<GraphQLTypeResolver<TSource, TContext, TArgs>>;
-  description?: Maybe<string>;
+  extensions?: Maybe<Readonly<Record<string, any>>>;
   astNode?: Maybe<InterfaceTypeDefinitionNode>;
   extensionASTNodes?: Maybe<ReadonlyArray<InterfaceTypeExtensionNode>>;
 }
@@ -598,9 +618,10 @@ export interface GraphQLInterfaceTypeConfig<
 export class GraphQLUnionType {
   name: string;
   description: Maybe<string>;
+  resolveType: Maybe<GraphQLTypeResolver<any, any>>;
+  extensions: Maybe<Readonly<Record<string, any>>>;
   astNode: Maybe<UnionTypeDefinitionNode>;
   extensionASTNodes: Maybe<ReadonlyArray<UnionTypeExtensionNode>>;
-  resolveType: Maybe<GraphQLTypeResolver<any, any>>;
 
   constructor(config: GraphQLUnionTypeConfig<any, any>);
 
@@ -618,6 +639,7 @@ export class GraphQLUnionType {
 
 export interface GraphQLUnionTypeConfig<TSource, TContext> {
   name: string;
+  description?: Maybe<string>;
   types: Thunk<GraphQLObjectType[]>;
   /**
    * Optionally provide a custom type resolver function. If one is not provided,
@@ -625,7 +647,7 @@ export interface GraphQLUnionTypeConfig<TSource, TContext> {
    * Object type.
    */
   resolveType?: Maybe<GraphQLTypeResolver<TSource, TContext>>;
-  description?: Maybe<string>;
+  extensions?: Maybe<Readonly<Record<string, any>>>;
   astNode?: Maybe<UnionTypeDefinitionNode>;
   extensionASTNodes?: Maybe<ReadonlyArray<UnionTypeExtensionNode>>;
 }
@@ -654,6 +676,7 @@ export interface GraphQLUnionTypeConfig<TSource, TContext> {
 export class GraphQLEnumType {
   name: string;
   description: Maybe<string>;
+  extensions: Maybe<Readonly<Record<string, any>>>;
   astNode: Maybe<EnumTypeDefinitionNode>;
   extensionASTNodes: Maybe<ReadonlyArray<EnumTypeExtensionNode>>;
 
@@ -678,8 +701,9 @@ export class GraphQLEnumType {
 
 export interface GraphQLEnumTypeConfig {
   name: string;
-  values: GraphQLEnumValueConfigMap;
   description?: Maybe<string>;
+  values: GraphQLEnumValueConfigMap;
+  extensions?: Maybe<Readonly<Record<string, any>>>;
   astNode?: Maybe<EnumTypeDefinitionNode>;
   extensionASTNodes?: Maybe<ReadonlyArray<EnumTypeExtensionNode>>;
 }
@@ -689,19 +713,21 @@ export type GraphQLEnumValueConfigMap = {
 };
 
 export interface GraphQLEnumValueConfig {
+  description?: Maybe<string>;
   value?: any;
   deprecationReason?: Maybe<string>;
-  description?: Maybe<string>;
+  extensions?: Maybe<Readonly<Record<string, any>>>;
   astNode?: Maybe<EnumValueDefinitionNode>;
 }
 
 export interface GraphQLEnumValue {
   name: string;
   description: Maybe<string>;
+  value: any;
   isDeprecated?: boolean;
   deprecationReason: Maybe<string>;
+  extensions: Maybe<Readonly<Record<string, any>>>;
   astNode?: Maybe<EnumValueDefinitionNode>;
-  value: any;
 }
 
 /**
@@ -727,6 +753,7 @@ export interface GraphQLEnumValue {
 export class GraphQLInputObjectType {
   name: string;
   description: Maybe<string>;
+  extensions: Maybe<Readonly<Record<string, any>>>;
   astNode: Maybe<InputObjectTypeDefinitionNode>;
   extensionASTNodes: Maybe<ReadonlyArray<InputObjectTypeExtensionNode>>;
   constructor(config: GraphQLInputObjectTypeConfig);
@@ -734,6 +761,7 @@ export class GraphQLInputObjectType {
 
   toConfig(): GraphQLInputObjectTypeConfig & {
     fields: GraphQLInputFieldConfigMap;
+    extensions: Maybe<Readonly<Record<string, any>>>;
     extensionASTNodes: ReadonlyArray<InputObjectTypeExtensionNode>;
   };
 
@@ -744,16 +772,18 @@ export class GraphQLInputObjectType {
 
 export interface GraphQLInputObjectTypeConfig {
   name: string;
-  fields: Thunk<GraphQLInputFieldConfigMap>;
   description?: Maybe<string>;
+  fields: Thunk<GraphQLInputFieldConfigMap>;
+  extensions?: Maybe<Readonly<Record<string, any>>>;
   astNode?: Maybe<InputObjectTypeDefinitionNode>;
   extensionASTNodes?: Maybe<ReadonlyArray<InputObjectTypeExtensionNode>>;
 }
 
 export interface GraphQLInputFieldConfig {
+  description?: Maybe<string>;
   type: GraphQLInputType;
   defaultValue?: any;
-  description?: Maybe<string>;
+  extensions?: Maybe<Readonly<Record<string, any>>>;
   astNode?: Maybe<InputValueDefinitionNode>;
 }
 
@@ -763,9 +793,10 @@ export type GraphQLInputFieldConfigMap = {
 
 export interface GraphQLInputField {
   name: string;
+  description?: Maybe<string>;
   type: GraphQLInputType;
   defaultValue?: any;
-  description?: Maybe<string>;
+  extensions: Maybe<Readonly<Record<string, any>>>;
   astNode?: Maybe<InputValueDefinitionNode>;
 }
 
diff --git a/tstypes/type/directives.d.ts b/tstypes/type/directives.d.ts
index c085aee35b..9719bf600e 100644
--- a/tstypes/type/directives.d.ts
+++ b/tstypes/type/directives.d.ts
@@ -7,7 +7,7 @@ import { DirectiveLocationEnum } from '../language/directiveLocation';
  * Test if the given value is a GraphQL directive.
  */
 export function isDirective(directive: any): directive is GraphQLDirective;
-
+export function assertDirective(directive: any): GraphQLDirective;
 /**
  * Directives are used by the GraphQL runtime as a way of modifying execution
  * behavior. Type system creators will usually not create these directly.
@@ -18,12 +18,17 @@ export class GraphQLDirective {
   locations: DirectiveLocationEnum[];
   isRepeatable: boolean;
   args: GraphQLArgument[];
+  extensions?: Maybe<Readonly<Record<string, any>>>;
   astNode: Maybe<DirectiveDefinitionNode>;
 
   constructor(config: GraphQLDirectiveConfig);
 
+  toString(): string;
+
   toConfig(): GraphQLDirectiveConfig & {
     args: GraphQLFieldConfigArgumentMap;
+    extensions?: Maybe<Readonly<Record<string, any>>>;
+    isRepeatable: boolean;
   };
 }
 
@@ -33,6 +38,7 @@ export interface GraphQLDirectiveConfig {
   locations: DirectiveLocationEnum[];
   args?: Maybe<GraphQLFieldConfigArgumentMap>;
   isRepeatable?: Maybe<boolean>;
+  extensions?: Maybe<Readonly<Record<string, any>>>;
   astNode?: Maybe<DirectiveDefinitionNode>;
 }
 
@@ -61,4 +67,6 @@ export const GraphQLDeprecatedDirective: GraphQLDirective;
  */
 export const specifiedDirectives: ReadonlyArray<GraphQLDirective>;
 
-export function isSpecifiedDirective(directive: GraphQLDirective): boolean;
+export function isSpecifiedDirective(
+  directive: any,
+): directive is GraphQLDirective;
diff --git a/tstypes/type/index.d.ts b/tstypes/type/index.d.ts
index 209582cb46..b6780d8171 100644
--- a/tstypes/type/index.d.ts
+++ b/tstypes/type/index.d.ts
@@ -1,6 +1,10 @@
+export { Path as ResponsePath } from '../jsutils/Path';
+
 export {
   // Predicate
   isSchema,
+  // Assertion
+  assertSchema,
   // GraphQL Schema definition
   GraphQLSchema,
   GraphQLSchemaConfig,
@@ -90,7 +94,6 @@ export {
   GraphQLIsTypeOfFn,
   GraphQLObjectTypeConfig,
   GraphQLResolveInfo,
-  ResponsePath,
   GraphQLScalarTypeConfig,
   GraphQLTypeResolver,
   GraphQLUnionTypeConfig,
@@ -102,6 +105,8 @@ export {
 export {
   // Predicate
   isDirective,
+  // Assertion
+  assertDirective,
   // Directives Definition
   GraphQLDirective,
   // Built-in Directives defined by the Spec
diff --git a/tstypes/type/introspection.d.ts b/tstypes/type/introspection.d.ts
index 9a4dd874ed..3acfe6e210 100644
--- a/tstypes/type/introspection.d.ts
+++ b/tstypes/type/introspection.d.ts
@@ -1,14 +1,9 @@
 import {
-  GraphQLScalarType,
   GraphQLObjectType,
-  GraphQLInterfaceType,
-  GraphQLUnionType,
+  GraphQLField,
   GraphQLEnumType,
-  GraphQLInputObjectType,
-  GraphQLList,
-  GraphQLNonNull,
+  GraphQLType,
 } from './definition';
-import { GraphQLField } from './definition';
 
 export const __Schema: GraphQLObjectType;
 export const __Directive: GraphQLObjectType;
@@ -40,6 +35,6 @@ export const SchemaMetaFieldDef: GraphQLField<any, any>;
 export const TypeMetaFieldDef: GraphQLField<any, any>;
 export const TypeNameMetaFieldDef: GraphQLField<any, any>;
 
-export const introspectionTypes: ReadonlyArray<any>;
+export const introspectionTypes: ReadonlyArray<GraphQLType>;
 
 export function isIntrospectionType(type: any): boolean;
diff --git a/tstypes/type/scalars.d.ts b/tstypes/type/scalars.d.ts
index 3cd8ad537c..fe16fd5cad 100644
--- a/tstypes/type/scalars.d.ts
+++ b/tstypes/type/scalars.d.ts
@@ -8,4 +8,4 @@ export const GraphQLID: GraphQLScalarType;
 
 export const specifiedScalarTypes: ReadonlyArray<GraphQLScalarType>;
 
-export function isSpecifiedScalarType(type: GraphQLScalarType): boolean;
+export function isSpecifiedScalarType(type: any): type is GraphQLScalarType;
diff --git a/tstypes/type/schema.d.ts b/tstypes/type/schema.d.ts
index 749eae4a92..5cbddaed60 100644
--- a/tstypes/type/schema.d.ts
+++ b/tstypes/type/schema.d.ts
@@ -1,17 +1,18 @@
 import Maybe from '../tsutils/Maybe';
-import { GraphQLObjectType } from './definition';
+import { SchemaDefinitionNode, SchemaExtensionNode } from '../language/ast';
+import { GraphQLDirective } from './directives';
 import {
   GraphQLType,
   GraphQLNamedType,
   GraphQLAbstractType,
+  GraphQLObjectType,
 } from './definition';
-import { SchemaDefinitionNode, SchemaExtensionNode } from '../language/ast';
-import { GraphQLDirective } from './directives';
 
 /**
  * Test if the given value is a GraphQL schema.
  */
 export function isSchema(schema: any): schema is GraphQLSchema;
+export function assertSchema(schema: any): GraphQLSchema;
 
 /**
  * Schema Definition
@@ -40,6 +41,7 @@ export function isSchema(schema: any): schema is GraphQLSchema;
  *
  */
 export class GraphQLSchema {
+  extensions: Maybe<Readonly<Record<string, any>>>;
   astNode: Maybe<SchemaDefinitionNode>;
   extensionASTNodes: Maybe<ReadonlyArray<SchemaExtensionNode>>;
 
@@ -65,7 +67,10 @@ export class GraphQLSchema {
   toConfig(): GraphQLSchemaConfig & {
     types: GraphQLNamedType[];
     directives: GraphQLDirective[];
+    extensions: Maybe<Readonly<Record<string, any>>>;
     extensionASTNodes: ReadonlyArray<SchemaExtensionNode>;
+    assumeValid: boolean;
+    allowedLegacyNames: ReadonlyArray<string>;
   };
 }
 
@@ -97,6 +102,7 @@ export interface GraphQLSchemaConfig extends GraphQLSchemaValidationOptions {
   subscription?: Maybe<GraphQLObjectType>;
   types?: Maybe<GraphQLNamedType[]>;
   directives?: Maybe<GraphQLDirective[]>;
+  extensions?: Maybe<Readonly<Record<string, any>>>;
   astNode?: Maybe<SchemaDefinitionNode>;
   extensionASTNodes?: Maybe<ReadonlyArray<SchemaExtensionNode>>;
 }
diff --git a/tstypes/type/validate.d.ts b/tstypes/type/validate.d.ts
index f6283f652a..9573befe3a 100644
--- a/tstypes/type/validate.d.ts
+++ b/tstypes/type/validate.d.ts
@@ -1,5 +1,5 @@
-import { GraphQLSchema } from './schema';
 import { GraphQLError } from '../error/GraphQLError';
+import { GraphQLSchema } from './schema';
 
 /**
  * Implements the "Type Validation" sub-sections of the specification's
diff --git a/tstypes/utilities/TypeInfo.d.ts b/tstypes/utilities/TypeInfo.d.ts
index 74d740b23d..1f2419b632 100644
--- a/tstypes/utilities/TypeInfo.d.ts
+++ b/tstypes/utilities/TypeInfo.d.ts
@@ -1,16 +1,16 @@
 import Maybe from '../tsutils/Maybe';
+import { ASTNode, FieldNode } from '../language/ast';
 import { GraphQLSchema } from '../type/schema';
+import { GraphQLDirective } from '../type/directives';
 import {
+  GraphQLType,
+  GraphQLInputType,
   GraphQLOutputType,
   GraphQLCompositeType,
-  GraphQLInputType,
   GraphQLField,
   GraphQLArgument,
   GraphQLEnumValue,
-  GraphQLType,
 } from '../type/definition';
-import { GraphQLDirective } from '../type/directives';
-import { ASTNode, FieldNode } from '../language/ast';
 
 /**
  * TypeInfo is a utility class which, given a GraphQL schema, can keep track
diff --git a/tstypes/utilities/buildASTSchema.d.ts b/tstypes/utilities/buildASTSchema.d.ts
index 9c4c58adb6..ec7e73e964 100644
--- a/tstypes/utilities/buildASTSchema.d.ts
+++ b/tstypes/utilities/buildASTSchema.d.ts
@@ -9,12 +9,16 @@ import {
   FieldDefinitionNode,
   InputValueDefinitionNode,
   EnumValueDefinitionNode,
+  TypeNode,
 } from '../language/ast';
 import {
   GraphQLNamedType,
   GraphQLFieldConfig,
   GraphQLInputField,
   GraphQLEnumValueConfig,
+  GraphQLType,
+  GraphQLArgumentConfig,
+  GraphQLInputFieldConfig,
 } from '../type/definition';
 import { GraphQLDirective } from '../type/directives';
 import { Source } from '../language/source';
@@ -66,25 +70,23 @@ type TypeDefinitionsMap = { [key: string]: TypeDefinitionNode };
 type TypeResolver = (typeRef: NamedTypeNode) => GraphQLNamedType;
 
 export class ASTDefinitionBuilder {
-  constructor(
-    typeDefinitionsMap: TypeDefinitionsMap,
-    options: Maybe<BuildSchemaOptions>,
-    resolveType: TypeResolver,
-  );
+  constructor(options: Maybe<BuildSchemaOptions>, resolveType: TypeResolver);
 
-  buildTypes(
-    nodes: ReadonlyArray<NamedTypeNode | TypeDefinitionNode>,
-  ): Array<GraphQLNamedType>;
+  getNamedType(node: NamedTypeNode): GraphQLNamedType;
 
-  buildType(node: NamedTypeNode | TypeDefinitionNode): GraphQLNamedType;
+  getWrappedType(node: TypeNode): GraphQLType;
 
-  buildDirective(directiveNode: DirectiveDefinitionNode): GraphQLDirective;
+  buildDirective(directive: DirectiveDefinitionNode): GraphQLDirective;
 
   buildField(field: FieldDefinitionNode): GraphQLFieldConfig<any, any>;
 
-  buildInputField(value: InputValueDefinitionNode): GraphQLInputField;
+  buildArg(value: InputValueDefinitionNode): GraphQLArgumentConfig;
+
+  buildInputField(value: InputValueDefinitionNode): GraphQLInputFieldConfig;
 
   buildEnumValue(value: EnumValueDefinitionNode): GraphQLEnumValueConfig;
+
+  buildType(node: NamedTypeNode | TypeDefinitionNode): GraphQLNamedType;
 }
 
 /**
diff --git a/tstypes/utilities/coerceInputValue.d.ts b/tstypes/utilities/coerceInputValue.d.ts
new file mode 100644
index 0000000000..cb8f1a581b
--- /dev/null
+++ b/tstypes/utilities/coerceInputValue.d.ts
@@ -0,0 +1,17 @@
+import { GraphQLInputType } from '../type/definition';
+import { GraphQLError } from 'tstypes/error';
+
+type OnErrorCB = (
+  path: ReadonlyArray<string | number>,
+  invalidValue: any,
+  error: GraphQLError,
+) => void;
+
+/**
+ * Coerces a JavaScript value given a GraphQL Input Type.
+ */
+export function coerceInputValue(
+  inputValue: any,
+  type: GraphQLInputType,
+  onError?: OnErrorCB,
+): any;
diff --git a/tstypes/utilities/coerceValue.d.ts b/tstypes/utilities/coerceValue.d.ts
index 96fafdca6a..f79389eac5 100644
--- a/tstypes/utilities/coerceValue.d.ts
+++ b/tstypes/utilities/coerceValue.d.ts
@@ -1,3 +1,4 @@
+import { Path } from '../jsutils/Path';
 import { GraphQLError } from '../error/GraphQLError';
 import { ASTNode } from '../language/ast';
 import { GraphQLInputType } from '../type/definition';
@@ -7,11 +8,6 @@ interface CoercedValue {
   readonly value: any;
 }
 
-interface Path {
-  readonly prev: Path | undefined;
-  readonly key: string | number;
-}
-
 /**
  * Coerces a JavaScript value given a GraphQL Type.
  *
@@ -20,7 +16,7 @@ interface Path {
  *
  */
 export function coerceValue(
-  value: any,
+  inputValue: any,
   type: GraphQLInputType,
   blameNode?: ASTNode,
   path?: Path,
diff --git a/tstypes/utilities/extendSchema.d.ts b/tstypes/utilities/extendSchema.d.ts
index 2f0007ba89..9df76c2ae4 100644
--- a/tstypes/utilities/extendSchema.d.ts
+++ b/tstypes/utilities/extendSchema.d.ts
@@ -1,6 +1,5 @@
 import { DocumentNode } from '../language/ast';
-import { GraphQLSchema } from '../type/schema';
-import { GraphQLSchemaValidationOptions } from '../type/schema';
+import { GraphQLSchemaValidationOptions, GraphQLSchema } from '../type/schema';
 
 interface Options extends GraphQLSchemaValidationOptions {
   /**
diff --git a/tstypes/utilities/findBreakingChanges.d.ts b/tstypes/utilities/findBreakingChanges.d.ts
index 75daa4f946..87fa0c028e 100644
--- a/tstypes/utilities/findBreakingChanges.d.ts
+++ b/tstypes/utilities/findBreakingChanges.d.ts
@@ -1,13 +1,3 @@
-import {
-  getNamedType,
-  GraphQLScalarType,
-  GraphQLEnumType,
-  GraphQLInputObjectType,
-  GraphQLInterfaceType,
-  GraphQLObjectType,
-  GraphQLUnionType,
-  GraphQLNamedType,
-} from '../type/definition';
 import { GraphQLDirective } from '../type/directives';
 import { GraphQLSchema } from '../type/schema';
 import { DirectiveLocationEnum } from '../language/directiveLocation';
@@ -16,33 +6,33 @@ export const BreakingChangeType: _BreakingChangeType;
 
 // @internal
 type _BreakingChangeType = {
-  FIELD_CHANGED_KIND: 'FIELD_CHANGED_KIND';
-  FIELD_REMOVED: 'FIELD_REMOVED';
-  TYPE_CHANGED_KIND: 'TYPE_CHANGED_KIND';
   TYPE_REMOVED: 'TYPE_REMOVED';
+  TYPE_CHANGED_KIND: 'TYPE_CHANGED_KIND';
   TYPE_REMOVED_FROM_UNION: 'TYPE_REMOVED_FROM_UNION';
   VALUE_REMOVED_FROM_ENUM: 'VALUE_REMOVED_FROM_ENUM';
-  ARG_REMOVED: 'ARG_REMOVED';
-  ARG_CHANGED_KIND: 'ARG_CHANGED_KIND';
-  REQUIRED_ARG_ADDED: 'REQUIRED_ARG_ADDED';
   REQUIRED_INPUT_FIELD_ADDED: 'REQUIRED_INPUT_FIELD_ADDED';
   INTERFACE_REMOVED_FROM_OBJECT: 'INTERFACE_REMOVED_FROM_OBJECT';
+  FIELD_REMOVED: 'FIELD_REMOVED';
+  FIELD_CHANGED_KIND: 'FIELD_CHANGED_KIND';
+  REQUIRED_ARG_ADDED: 'REQUIRED_ARG_ADDED';
+  ARG_REMOVED: 'ARG_REMOVED';
+  ARG_CHANGED_KIND: 'ARG_CHANGED_KIND';
   DIRECTIVE_REMOVED: 'DIRECTIVE_REMOVED';
   DIRECTIVE_ARG_REMOVED: 'DIRECTIVE_ARG_REMOVED';
-  DIRECTIVE_LOCATION_REMOVED: 'DIRECTIVE_LOCATION_REMOVED';
   REQUIRED_DIRECTIVE_ARG_ADDED: 'REQUIRED_DIRECTIVE_ARG_ADDED';
+  DIRECTIVE_LOCATION_REMOVED: 'DIRECTIVE_LOCATION_REMOVED';
 };
 
 export const DangerousChangeType: _DangerousChangeType;
 
 // @internal
 type _DangerousChangeType = {
-  ARG_DEFAULT_VALUE_CHANGE: 'ARG_DEFAULT_VALUE_CHANGE';
   VALUE_ADDED_TO_ENUM: 'VALUE_ADDED_TO_ENUM';
-  INTERFACE_ADDED_TO_OBJECT: 'INTERFACE_ADDED_TO_OBJECT';
   TYPE_ADDED_TO_UNION: 'TYPE_ADDED_TO_UNION';
   OPTIONAL_INPUT_FIELD_ADDED: 'OPTIONAL_INPUT_FIELD_ADDED';
   OPTIONAL_ARG_ADDED: 'OPTIONAL_ARG_ADDED';
+  INTERFACE_ADDED_TO_OBJECT: 'INTERFACE_ADDED_TO_OBJECT';
+  ARG_DEFAULT_VALUE_CHANGE: 'ARG_DEFAULT_VALUE_CHANGE';
 };
 
 export interface BreakingChange {
@@ -72,119 +62,3 @@ export function findDangerousChanges(
   oldSchema: GraphQLSchema,
   newSchema: GraphQLSchema,
 ): Array<DangerousChange>;
-
-/**
- * Given two schemas, returns an Array containing descriptions of any breaking
- * changes in the newSchema related to removing an entire type.
- */
-export function findRemovedTypes(
-  oldSchema: GraphQLSchema,
-  newSchema: GraphQLSchema,
-): Array<BreakingChange>;
-
-/**
- * Given two schemas, returns an Array containing descriptions of any breaking
- * changes in the newSchema related to changing the type of a type.
- */
-export function findTypesThatChangedKind(
-  oldSchema: GraphQLSchema,
-  newSchema: GraphQLSchema,
-): Array<BreakingChange>;
-
-/**
- * Given two schemas, returns an Array containing descriptions of any
- * breaking or dangerous changes in the newSchema related to arguments
- * (such as removal or change of type of an argument, or a change in an
- * argument's default value).
- */
-export function findArgChanges(
-  oldSchema: GraphQLSchema,
-  newSchema: GraphQLSchema,
-): {
-  breakingChanges: Array<BreakingChange>;
-  dangerousChanges: Array<DangerousChange>;
-};
-
-export function findFieldsThatChangedTypeOnObjectOrInterfaceTypes(
-  oldSchema: GraphQLSchema,
-  newSchema: GraphQLSchema,
-): Array<BreakingChange>;
-
-export function findFieldsThatChangedTypeOnInputObjectTypes(
-  oldSchema: GraphQLSchema,
-  newSchema: GraphQLSchema,
-): {
-  breakingChanges: Array<BreakingChange>;
-  dangerousChanges: Array<DangerousChange>;
-};
-
-/**
- * Given two schemas, returns an Array containing descriptions of any breaking
- * changes in the newSchema related to removing types from a union type.
- */
-export function findTypesRemovedFromUnions(
-  oldSchema: GraphQLSchema,
-  newSchema: GraphQLSchema,
-): Array<BreakingChange>;
-
-/**
- * Given two schemas, returns an Array containing descriptions of any dangerous
- * changes in the newSchema related to adding types to a union type.
- */
-export function findTypesAddedToUnions(
-  oldSchema: GraphQLSchema,
-  newSchema: GraphQLSchema,
-): Array<DangerousChange>;
-
-/**
- * Given two schemas, returns an Array containing descriptions of any breaking
- * changes in the newSchema related to removing values from an enum type.
- */
-export function findValuesRemovedFromEnums(
-  oldSchema: GraphQLSchema,
-  newSchema: GraphQLSchema,
-): Array<BreakingChange>;
-
-/**
- * Given two schemas, returns an Array containing descriptions of any dangerous
- * changes in the newSchema related to adding values to an enum type.
- */
-export function findValuesAddedToEnums(
-  oldSchema: GraphQLSchema,
-  newSchema: GraphQLSchema,
-): Array<DangerousChange>;
-
-export function findInterfacesRemovedFromObjectTypes(
-  oldSchema: GraphQLSchema,
-  newSchema: GraphQLSchema,
-): Array<BreakingChange>;
-
-export function findInterfacesAddedToObjectTypes(
-  oldSchema: GraphQLSchema,
-  newSchema: GraphQLSchema,
-): Array<DangerousChange>;
-
-export function findRemovedDirectives(
-  oldSchema: GraphQLSchema,
-  newSchema: GraphQLSchema,
-): Array<BreakingChange>;
-
-export function findRemovedDirectiveArgs(
-  oldSchema: GraphQLSchema,
-  newSchema: GraphQLSchema,
-): Array<BreakingChange>;
-
-export function findAddedNonNullDirectiveArgs(
-  oldSchema: GraphQLSchema,
-  newSchema: GraphQLSchema,
-): Array<BreakingChange>;
-
-export function findRemovedLocationsForDirective(
-  oldDirective: GraphQLDirective,
-  newDirective: GraphQLDirective,
-): Array<DirectiveLocationEnum>;
-
-export function findRemovedDirectiveLocations(
-  oldSchema: GraphQLSchema,
-  newSchema: GraphQLSchema,
-): Array<BreakingChange>;
diff --git a/tstypes/utilities/findDeprecatedUsages.d.ts b/tstypes/utilities/findDeprecatedUsages.d.ts
index 8cd844e15f..0a55f1b82d 100644
--- a/tstypes/utilities/findDeprecatedUsages.d.ts
+++ b/tstypes/utilities/findDeprecatedUsages.d.ts
@@ -1,6 +1,6 @@
-import { GraphQLSchema } from '../type/schema';
-import { DocumentNode } from '../language/ast';
 import { GraphQLError } from '../error/GraphQLError';
+import { DocumentNode } from '../language/ast';
+import { GraphQLSchema } from '../type/schema';
 
 /**
  * A validation rule which reports deprecated usages.
diff --git a/tstypes/utilities/getOperationRootType.d.ts b/tstypes/utilities/getOperationRootType.d.ts
index f82eeecbc1..5adc59c7af 100644
--- a/tstypes/utilities/getOperationRootType.d.ts
+++ b/tstypes/utilities/getOperationRootType.d.ts
@@ -1,8 +1,8 @@
-import { GraphQLSchema } from '../type/schema';
 import {
   OperationDefinitionNode,
   OperationTypeDefinitionNode,
 } from '../language/ast';
+import { GraphQLSchema } from '../type/schema';
 import { GraphQLObjectType } from '../type/definition';
 
 /**
diff --git a/tstypes/utilities/index.d.ts b/tstypes/utilities/index.d.ts
index a459298c5b..f3d82f01ec 100644
--- a/tstypes/utilities/index.d.ts
+++ b/tstypes/utilities/index.d.ts
@@ -81,6 +81,9 @@ export { astFromValue } from './astFromValue';
 // the GraphQL type system.
 export { TypeInfo } from './TypeInfo';
 
+// Coerces a JavaScript value to a GraphQL type, or produces errors.
+export { coerceInputValue } from './coerceInputValue';
+
 // Coerces a JavaScript value to a GraphQL type, or produces errors.
 export { coerceValue } from './coerceValue';
 
@@ -96,6 +99,10 @@ export { concatAST } from './concatAST';
 // Separates an AST into an AST per Operation.
 export { separateOperations } from './separateOperations';
 
+// Strips characters that are not significant to the validity or execution
+// of a GraphQL document.
+export { stripIgnoredCharacters } from './stripIgnoredCharacters';
+
 // Comparators for types
 export {
   isEqualType,
diff --git a/tstypes/utilities/separateOperations.d.ts b/tstypes/utilities/separateOperations.d.ts
index d3dcb6e957..28654fdb1b 100644
--- a/tstypes/utilities/separateOperations.d.ts
+++ b/tstypes/utilities/separateOperations.d.ts
@@ -1,4 +1,4 @@
-import { DocumentNode, OperationDefinitionNode } from '../language/ast';
+import { DocumentNode } from '../language/ast';
 
 /**
  * separateOperations accepts a single AST document which may contain many
diff --git a/tstypes/utilities/stripIgnoredCharacters.d.ts b/tstypes/utilities/stripIgnoredCharacters.d.ts
new file mode 100644
index 0000000000..a131af02f5
--- /dev/null
+++ b/tstypes/utilities/stripIgnoredCharacters.d.ts
@@ -0,0 +1,55 @@
+import { Source } from '../language/source';
+
+/**
+ * Strips characters that are not significant to the validity or execution
+ * of a GraphQL document:
+ *   - UnicodeBOM
+ *   - WhiteSpace
+ *   - LineTerminator
+ *   - Comment
+ *   - Comma
+ *   - BlockString indentation
+ *
+ * Note: It is required to have a delimiter character between neighboring
+ * non-punctuator tokens and this function always uses single space as delimiter.
+ *
+ * It is guaranteed that both input and output documents if parsed would result
+ * in the exact same AST except for nodes location.
+ *
+ * Warning: It is guaranteed that this function will always produce stable results.
+ * However, it's not guaranteed that it will stay the same between different
+ * releases due to bugfixes or changes in the GraphQL specification.
+ *
+ * Query example:
+ *
+ * query SomeQuery($foo: String!, $bar: String) {
+ *   someField(foo: $foo, bar: $bar) {
+ *     a
+ *     b {
+ *       c
+ *       d
+ *     }
+ *   }
+ * }
+ *
+ * Becomes:
+ *
+ * query SomeQuery($foo:String!$bar:String){someField(foo:$foo bar:$bar){a b{c d}}}
+ *
+ * SDL example:
+ *
+ * """
+ * Type description
+ * """
+ * type Foo {
+ *   """
+ *   Field description
+ *   """
+ *   bar: String
+ * }
+ *
+ * Becomes:
+ *
+ * """Type description""" type Foo{"""Field description""" bar:String}
+ */
+export function stripIgnoredCharacters(source: string | Source): string;
diff --git a/tstypes/utilities/typeComparators.d.ts b/tstypes/utilities/typeComparators.d.ts
index ca0cdaf6c2..7de3e00b68 100644
--- a/tstypes/utilities/typeComparators.d.ts
+++ b/tstypes/utilities/typeComparators.d.ts
@@ -1,9 +1,5 @@
-import {
-  GraphQLType,
-  GraphQLCompositeType,
-  GraphQLAbstractType,
-} from '../type/definition';
 import { GraphQLSchema } from '../type/schema';
+import { GraphQLType, GraphQLCompositeType } from '../type/definition';
 
 /**
  * Provided two types, return true if the types are equal (invariant).
diff --git a/tstypes/utilities/typeFromAST.d.ts b/tstypes/utilities/typeFromAST.d.ts
index 10e467dee9..cf32ac7cee 100644
--- a/tstypes/utilities/typeFromAST.d.ts
+++ b/tstypes/utilities/typeFromAST.d.ts
@@ -1,17 +1,10 @@
+import { NamedTypeNode, ListTypeNode, NonNullTypeNode } from '../language/ast';
+import { GraphQLSchema } from '../type/schema';
 import {
-  TypeNode,
-  NamedTypeNode,
-  ListTypeNode,
-  NonNullTypeNode,
-} from '../language/ast';
-import {
-  GraphQLType,
-  GraphQLNullableType,
   GraphQLNamedType,
   GraphQLList,
   GraphQLNonNull,
 } from '../type/definition';
-import { GraphQLSchema } from '../type/schema';
 
 /**
  * Given a Schema and an AST node describing a type, return a GraphQLType
diff --git a/tstypes/utilities/valueFromAST.d.ts b/tstypes/utilities/valueFromAST.d.ts
index 06a130aebf..bef11b75d3 100644
--- a/tstypes/utilities/valueFromAST.d.ts
+++ b/tstypes/utilities/valueFromAST.d.ts
@@ -1,11 +1,6 @@
 import Maybe from '../tsutils/Maybe';
+import { ValueNode } from '../language/ast';
 import { GraphQLInputType } from '../type/definition';
-import {
-  ValueNode,
-  VariableNode,
-  ListValueNode,
-  ObjectValueNode,
-} from '../language/ast';
 
 /**
  * Produces a JavaScript value given a GraphQL Value AST.
diff --git a/tstypes/validation/ValidationContext.d.ts b/tstypes/validation/ValidationContext.d.ts
index 1576bdc64e..b98c947b7f 100644
--- a/tstypes/validation/ValidationContext.d.ts
+++ b/tstypes/validation/ValidationContext.d.ts
@@ -1,5 +1,6 @@
 import Maybe from '../tsutils/Maybe';
 import { GraphQLError } from '../error';
+import { ASTVisitor } from '../language/visitor';
 import {
   DocumentNode,
   OperationDefinitionNode,
@@ -9,6 +10,7 @@ import {
   FragmentDefinitionNode,
 } from '../language/ast';
 import { GraphQLSchema } from '../type/schema';
+import { GraphQLDirective } from '../type/directives';
 import {
   GraphQLInputType,
   GraphQLOutputType,
@@ -16,9 +18,7 @@ import {
   GraphQLField,
   GraphQLArgument,
 } from '../type/definition';
-import { GraphQLDirective } from '../type/directives';
 import { TypeInfo } from '../utilities/TypeInfo';
-import { ASTVisitor } from '../language/visitor';
 
 type NodeWithSelectionSet = OperationDefinitionNode | FragmentDefinitionNode;
 type VariableUsage = {
@@ -40,10 +40,22 @@ export class ASTValidationContext {
   getErrors(): ReadonlyArray<GraphQLError>;
 
   getDocument(): DocumentNode;
+
+  getFragment(name: string): Maybe<FragmentDefinitionNode>;
+
+  getFragmentSpreads(node: SelectionSetNode): ReadonlyArray<FragmentSpreadNode>;
+
+  getRecursivelyReferencedFragments(
+    operation: OperationDefinitionNode,
+  ): ReadonlyArray<FragmentDefinitionNode>;
 }
 
 export class SDLValidationContext extends ASTValidationContext {
-  constructor(ast: DocumentNode, schema?: Maybe<GraphQLSchema>);
+  constructor(
+    ast: DocumentNode,
+    schema: Maybe<GraphQLSchema>,
+    onError?: (err: GraphQLError) => void,
+  );
 
   getSchema(): Maybe<GraphQLSchema>;
 }
@@ -51,24 +63,21 @@ export class SDLValidationContext extends ASTValidationContext {
 export type SDLValidationRule = (context: SDLValidationContext) => ASTVisitor;
 
 export class ValidationContext extends ASTValidationContext {
-  constructor(schema: GraphQLSchema, ast: DocumentNode, typeInfo: TypeInfo);
+  constructor(
+    schema: GraphQLSchema,
+    ast: DocumentNode,
+    typeInfo: TypeInfo,
+    onError?: (err: GraphQLError) => void,
+  );
 
   getSchema(): GraphQLSchema;
 
-  getFragment(name: string): Maybe<FragmentDefinitionNode>;
-
-  getFragmentSpreads(node: SelectionSetNode): ReadonlyArray<FragmentSpreadNode>;
+  getVariableUsages(node: NodeWithSelectionSet): ReadonlyArray<VariableUsage>;
 
   getRecursivelyReferencedFragments(
     operation: OperationDefinitionNode,
   ): ReadonlyArray<FragmentDefinitionNode>;
 
-  getVariableUsages(node: NodeWithSelectionSet): ReadonlyArray<VariableUsage>;
-
-  getRecursiveVariableUsages(
-    operation: OperationDefinitionNode,
-  ): ReadonlyArray<VariableUsage>;
-
   getType(): Maybe<GraphQLOutputType>;
 
   getParentType(): Maybe<GraphQLCompositeType>;
diff --git a/tstypes/validation/index.d.ts b/tstypes/validation/index.d.ts
index 3d8f38e80d..3c6d260df6 100644
--- a/tstypes/validation/index.d.ts
+++ b/tstypes/validation/index.d.ts
@@ -1,6 +1,6 @@
 export { validate } from './validate';
 
-export { ValidationContext } from './ValidationContext';
+export { ValidationContext, ValidationRule } from './ValidationContext';
 
 export { specifiedRules } from './specifiedRules';
 
diff --git a/tstypes/validation/rules/ExecutableDefinitions.d.ts b/tstypes/validation/rules/ExecutableDefinitions.d.ts
index 055bca6e63..e079dea2f0 100644
--- a/tstypes/validation/rules/ExecutableDefinitions.d.ts
+++ b/tstypes/validation/rules/ExecutableDefinitions.d.ts
@@ -1,5 +1,5 @@
-import { ASTValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ASTValidationContext } from '../ValidationContext';
 
 export function nonExecutableDefinitionMessage(defName: string): string;
 
diff --git a/tstypes/validation/rules/FieldsOnCorrectType.d.ts b/tstypes/validation/rules/FieldsOnCorrectType.d.ts
index 38ba3ed846..130cb83d13 100644
--- a/tstypes/validation/rules/FieldsOnCorrectType.d.ts
+++ b/tstypes/validation/rules/FieldsOnCorrectType.d.ts
@@ -1,5 +1,12 @@
-import { ValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ValidationContext } from '../ValidationContext';
+
+export function undefinedFieldMessage(
+  fieldName: string,
+  type: string,
+  suggestedTypeNames: ReadonlyArray<string>,
+  suggestedFieldNames: ReadonlyArray<string>,
+): string;
 
 /**
  * Fields on correct type
diff --git a/tstypes/validation/rules/FragmentsOnCompositeTypes.d.ts b/tstypes/validation/rules/FragmentsOnCompositeTypes.d.ts
index f2da30fd00..32bd7c7f7d 100644
--- a/tstypes/validation/rules/FragmentsOnCompositeTypes.d.ts
+++ b/tstypes/validation/rules/FragmentsOnCompositeTypes.d.ts
@@ -1,5 +1,5 @@
-import { ValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ValidationContext } from '../ValidationContext';
 
 export function inlineFragmentOnNonCompositeErrorMessage(type: string): string;
 
diff --git a/tstypes/validation/rules/KnownArgumentNames.d.ts b/tstypes/validation/rules/KnownArgumentNames.d.ts
index 208f919302..e3869ca72e 100644
--- a/tstypes/validation/rules/KnownArgumentNames.d.ts
+++ b/tstypes/validation/rules/KnownArgumentNames.d.ts
@@ -5,13 +5,13 @@ export function unknownArgMessage(
   argName: string,
   fieldName: string,
   typeName: string,
-  suggestedArgs: Array<string>,
+  suggestedArgs: ReadonlyArray<string>,
 ): string;
 
 export function unknownDirectiveArgMessage(
   argName: string,
   directiveName: string,
-  suggestedArgs: Array<string>,
+  suggestedArgs: ReadonlyArray<string>,
 ): string;
 
 /**
diff --git a/tstypes/validation/rules/KnownDirectives.d.ts b/tstypes/validation/rules/KnownDirectives.d.ts
index 8585a80737..ecff9172a2 100644
--- a/tstypes/validation/rules/KnownDirectives.d.ts
+++ b/tstypes/validation/rules/KnownDirectives.d.ts
@@ -1,5 +1,5 @@
-import { ValidationContext, SDLValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ValidationContext, SDLValidationContext } from '../ValidationContext';
 
 export function unknownDirectiveMessage(directiveName: string): string;
 
diff --git a/tstypes/validation/rules/KnownFragmentNames.d.ts b/tstypes/validation/rules/KnownFragmentNames.d.ts
index 14168e2348..0f91fd895a 100644
--- a/tstypes/validation/rules/KnownFragmentNames.d.ts
+++ b/tstypes/validation/rules/KnownFragmentNames.d.ts
@@ -1,5 +1,5 @@
-import { ValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ValidationContext } from '../ValidationContext';
 
 export function unknownFragmentMessage(fragName: string): string;
 
diff --git a/tstypes/validation/rules/KnownTypeNames.d.ts b/tstypes/validation/rules/KnownTypeNames.d.ts
index d720269f9b..cc8280db0f 100644
--- a/tstypes/validation/rules/KnownTypeNames.d.ts
+++ b/tstypes/validation/rules/KnownTypeNames.d.ts
@@ -1,5 +1,5 @@
-import { ValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ValidationContext } from '../ValidationContext';
 
 export function unknownTypeMessage(
   typeName: string,
diff --git a/tstypes/validation/rules/LoneAnonymousOperation.d.ts b/tstypes/validation/rules/LoneAnonymousOperation.d.ts
index 345966ad7d..ed1ce2505b 100644
--- a/tstypes/validation/rules/LoneAnonymousOperation.d.ts
+++ b/tstypes/validation/rules/LoneAnonymousOperation.d.ts
@@ -1,5 +1,5 @@
-import { ASTValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ASTValidationContext } from '../ValidationContext';
 
 export function anonOperationNotAloneMessage(): string;
 
diff --git a/tstypes/validation/rules/LoneSchemaDefinition.d.ts b/tstypes/validation/rules/LoneSchemaDefinition.d.ts
index c2084bb5eb..fab68bee8d 100644
--- a/tstypes/validation/rules/LoneSchemaDefinition.d.ts
+++ b/tstypes/validation/rules/LoneSchemaDefinition.d.ts
@@ -1,5 +1,5 @@
-import { SDLValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { SDLValidationContext } from '../ValidationContext';
 
 export function schemaDefinitionNotAloneMessage(): string;
 
diff --git a/tstypes/validation/rules/NoFragmentCycles.d.ts b/tstypes/validation/rules/NoFragmentCycles.d.ts
index 98e9051722..80eff89fa6 100644
--- a/tstypes/validation/rules/NoFragmentCycles.d.ts
+++ b/tstypes/validation/rules/NoFragmentCycles.d.ts
@@ -1,9 +1,9 @@
-import { ValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ValidationContext } from '../ValidationContext';
 
 export function cycleErrorMessage(
   fragName: string,
-  spreadNames: Array<string>,
+  spreadNames: ReadonlyArray<string>,
 ): string;
 
 export function NoFragmentCycles(context: ValidationContext): ASTVisitor;
diff --git a/tstypes/validation/rules/NoUndefinedVariables.d.ts b/tstypes/validation/rules/NoUndefinedVariables.d.ts
index a8bd4d9d95..54797d3d6c 100644
--- a/tstypes/validation/rules/NoUndefinedVariables.d.ts
+++ b/tstypes/validation/rules/NoUndefinedVariables.d.ts
@@ -1,6 +1,6 @@
 import Maybe from '../../tsutils/Maybe';
-import { ValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ValidationContext } from '../ValidationContext';
 
 export function undefinedVarMessage(
   varName: string,
diff --git a/tstypes/validation/rules/NoUnusedFragments.d.ts b/tstypes/validation/rules/NoUnusedFragments.d.ts
index be44a0cb83..8c9631e8bd 100644
--- a/tstypes/validation/rules/NoUnusedFragments.d.ts
+++ b/tstypes/validation/rules/NoUnusedFragments.d.ts
@@ -1,5 +1,5 @@
-import { ValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ValidationContext } from '../ValidationContext';
 
 export function unusedFragMessage(fragName: string): string;
 
diff --git a/tstypes/validation/rules/NoUnusedVariables.d.ts b/tstypes/validation/rules/NoUnusedVariables.d.ts
index 4d2c9be1c8..055faa1145 100644
--- a/tstypes/validation/rules/NoUnusedVariables.d.ts
+++ b/tstypes/validation/rules/NoUnusedVariables.d.ts
@@ -1,6 +1,6 @@
 import Maybe from '../../tsutils/Maybe';
-import { ValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ValidationContext } from '../ValidationContext';
 
 export function unusedVariableMessage(
   varName: string,
diff --git a/tstypes/validation/rules/OverlappingFieldsCanBeMerged.d.ts b/tstypes/validation/rules/OverlappingFieldsCanBeMerged.d.ts
index 1288ed1da7..b581ee9c43 100644
--- a/tstypes/validation/rules/OverlappingFieldsCanBeMerged.d.ts
+++ b/tstypes/validation/rules/OverlappingFieldsCanBeMerged.d.ts
@@ -1,5 +1,5 @@
-import { ValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ValidationContext } from '../ValidationContext';
 
 export function fieldsConflictMessage(
   responseName: string,
diff --git a/tstypes/validation/rules/PossibleFragmentSpreads.d.ts b/tstypes/validation/rules/PossibleFragmentSpreads.d.ts
index 1623fc41d8..cd1a3fc074 100644
--- a/tstypes/validation/rules/PossibleFragmentSpreads.d.ts
+++ b/tstypes/validation/rules/PossibleFragmentSpreads.d.ts
@@ -1,5 +1,5 @@
-import { ValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ValidationContext } from '../ValidationContext';
 
 export function typeIncompatibleSpreadMessage(
   fragName: string,
diff --git a/tstypes/validation/rules/PossibleTypeExtensions.d.ts b/tstypes/validation/rules/PossibleTypeExtensions.d.ts
new file mode 100644
index 0000000000..0bb4328f19
--- /dev/null
+++ b/tstypes/validation/rules/PossibleTypeExtensions.d.ts
@@ -0,0 +1,21 @@
+import { ASTVisitor } from '../../language/visitor';
+import { SDLValidationContext } from '../ValidationContext';
+
+export function extendingUnknownTypeMessage(
+  typeName: string,
+  suggestedTypes: $ReadOnlyArray<string>,
+): string;
+
+export function extendingDifferentTypeKindMessage(
+  typeName: string,
+  kind: string,
+): string;
+
+/**
+ * Possible type extension
+ *
+ * A type extension is only valid if the type is defined and has the same kind.
+ */
+export function PossibleTypeExtensions(
+  context: SDLValidationContext,
+): ASTVisitor;
diff --git a/tstypes/validation/rules/ProvidedRequiredArguments.d.ts b/tstypes/validation/rules/ProvidedRequiredArguments.d.ts
index a7382f2af7..c1bc4c4683 100644
--- a/tstypes/validation/rules/ProvidedRequiredArguments.d.ts
+++ b/tstypes/validation/rules/ProvidedRequiredArguments.d.ts
@@ -1,5 +1,5 @@
-import { ValidationContext, SDLValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ValidationContext, SDLValidationContext } from '../ValidationContext';
 
 export function missingFieldArgMessage(
   fieldName: string,
diff --git a/tstypes/validation/rules/ScalarLeafs.d.ts b/tstypes/validation/rules/ScalarLeafs.d.ts
index c16d923811..f01448beef 100644
--- a/tstypes/validation/rules/ScalarLeafs.d.ts
+++ b/tstypes/validation/rules/ScalarLeafs.d.ts
@@ -1,5 +1,5 @@
-import { ValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ValidationContext } from '../ValidationContext';
 
 export function noSubselectionAllowedMessage(
   fieldName: string,
diff --git a/tstypes/validation/rules/SingleFieldSubscriptions.d.ts b/tstypes/validation/rules/SingleFieldSubscriptions.d.ts
index 8e3d56c3b1..7dbbb23cf3 100644
--- a/tstypes/validation/rules/SingleFieldSubscriptions.d.ts
+++ b/tstypes/validation/rules/SingleFieldSubscriptions.d.ts
@@ -1,6 +1,6 @@
 import Maybe from '../../tsutils/Maybe';
-import { ASTValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ASTValidationContext } from '../ValidationContext';
 
 export function singleFieldOnlyMessage(name: Maybe<string>): string;
 
diff --git a/tstypes/validation/rules/UniqueArgumentNames.d.ts b/tstypes/validation/rules/UniqueArgumentNames.d.ts
index f0b4d4adc2..fdd51e1020 100644
--- a/tstypes/validation/rules/UniqueArgumentNames.d.ts
+++ b/tstypes/validation/rules/UniqueArgumentNames.d.ts
@@ -1,5 +1,5 @@
-import { ASTValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ASTValidationContext } from '../ValidationContext';
 
 export function duplicateArgMessage(argName: string): string;
 
diff --git a/tstypes/validation/rules/UniqueDirectiveNames.d.ts b/tstypes/validation/rules/UniqueDirectiveNames.d.ts
new file mode 100644
index 0000000000..3490938491
--- /dev/null
+++ b/tstypes/validation/rules/UniqueDirectiveNames.d.ts
@@ -0,0 +1,13 @@
+import { ASTVisitor } from '../../language/visitor';
+import { ASTValidationContext } from '../ValidationContext';
+
+export function duplicateDirectiveNameMessage(directiveName: string): string;
+
+export function existedDirectiveNameMessage(directiveName: string): string;
+
+/**
+ * Unique directive names
+ *
+ * A GraphQL document is only valid if all defined directives have unique names.
+ */
+export function UniqueDirectiveNames(context: SDLValidationContext): ASTVisitor;
diff --git a/tstypes/validation/rules/UniqueDirectivesPerLocation.d.ts b/tstypes/validation/rules/UniqueDirectivesPerLocation.d.ts
index 879eea7eeb..02c73123cd 100644
--- a/tstypes/validation/rules/UniqueDirectivesPerLocation.d.ts
+++ b/tstypes/validation/rules/UniqueDirectivesPerLocation.d.ts
@@ -1,5 +1,5 @@
-import { ASTValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ASTValidationContext } from '../ValidationContext';
 
 export function duplicateDirectiveMessage(directiveName: string): string;
 
diff --git a/tstypes/validation/rules/UniqueEnumValueNames.d.ts b/tstypes/validation/rules/UniqueEnumValueNames.d.ts
new file mode 100644
index 0000000000..2f3f654092
--- /dev/null
+++ b/tstypes/validation/rules/UniqueEnumValueNames.d.ts
@@ -0,0 +1,19 @@
+import { ASTVisitor } from '../../language/visitor';
+import { SDLValidationContext } from '../ValidationContext';
+
+export function duplicateEnumValueNameMessage(
+  typeName: string,
+  valueName: string,
+): string;
+
+export function existedEnumValueNameMessage(
+  typeName: string,
+  valueName: string,
+): string;
+
+/**
+ * Unique enum value names
+ *
+ * A GraphQL enum type is only valid if all its values are uniquely named.
+ */
+export function UniqueEnumValueNames(context: SDLValidationContext): ASTVisitor;
diff --git a/tstypes/validation/rules/UniqueFieldDefinitionNames.d.ts b/tstypes/validation/rules/UniqueFieldDefinitionNames.d.ts
new file mode 100644
index 0000000000..11d6e4fb64
--- /dev/null
+++ b/tstypes/validation/rules/UniqueFieldDefinitionNames.d.ts
@@ -0,0 +1,21 @@
+import { ASTVisitor } from '../../language/visitor';
+import { SDLValidationContext } from '../ValidationContext';
+
+export function duplicateFieldDefinitionNameMessage(
+  typeName: string,
+  fieldName: string,
+): string;
+
+export function existedFieldDefinitionNameMessage(
+  typeName: string,
+  fieldName: string,
+): string;
+
+/**
+ * Unique field definition names
+ *
+ * A GraphQL complex type is only valid if all its fields are uniquely named.
+ */
+export function UniqueFieldDefinitionNames(
+  context: SDLValidationContext,
+): ASTVisitor;
diff --git a/tstypes/validation/rules/UniqueFragmentNames.d.ts b/tstypes/validation/rules/UniqueFragmentNames.d.ts
index e849d9fe32..ebd4bb2d6e 100644
--- a/tstypes/validation/rules/UniqueFragmentNames.d.ts
+++ b/tstypes/validation/rules/UniqueFragmentNames.d.ts
@@ -1,5 +1,5 @@
-import { ASTValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ASTValidationContext } from '../ValidationContext';
 
 export function duplicateFragmentNameMessage(fragName: string): string;
 
diff --git a/tstypes/validation/rules/UniqueInputFieldNames.d.ts b/tstypes/validation/rules/UniqueInputFieldNames.d.ts
index d2682fec0b..3894428ca8 100644
--- a/tstypes/validation/rules/UniqueInputFieldNames.d.ts
+++ b/tstypes/validation/rules/UniqueInputFieldNames.d.ts
@@ -1,5 +1,5 @@
-import { ASTValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ASTValidationContext } from '../ValidationContext';
 
 export function duplicateInputFieldMessage(fieldName: string): string;
 
diff --git a/tstypes/validation/rules/UniqueOperationNames.d.ts b/tstypes/validation/rules/UniqueOperationNames.d.ts
index bd31be1ee2..0c6234965a 100644
--- a/tstypes/validation/rules/UniqueOperationNames.d.ts
+++ b/tstypes/validation/rules/UniqueOperationNames.d.ts
@@ -1,5 +1,5 @@
-import { ASTValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ASTValidationContext } from '../ValidationContext';
 
 export function duplicateOperationNameMessage(operationName: string): string;
 
diff --git a/tstypes/validation/rules/UniqueOperationTypes.d.ts b/tstypes/validation/rules/UniqueOperationTypes.d.ts
new file mode 100644
index 0000000000..fef615bbc1
--- /dev/null
+++ b/tstypes/validation/rules/UniqueOperationTypes.d.ts
@@ -0,0 +1,13 @@
+import { ASTVisitor } from '../../language/visitor';
+import { SDLValidationContext } from '../ValidationContext';
+
+export function duplicateOperationTypeMessage(operation: string): string;
+
+export function existedOperationTypeMessage(operation: string): string;
+
+/**
+ * Unique operation types
+ *
+ * A GraphQL document is only valid if it has only one type per operation.
+ */
+export function UniqueOperationTypes(context: SDLValidationContext): ASTVisitor;
diff --git a/tstypes/validation/rules/UniqueTypeNames.d.ts b/tstypes/validation/rules/UniqueTypeNames.d.ts
new file mode 100644
index 0000000000..8b9e3ad3ab
--- /dev/null
+++ b/tstypes/validation/rules/UniqueTypeNames.d.ts
@@ -0,0 +1,13 @@
+import { ASTVisitor } from '../../language/visitor';
+import { SDLValidationContext } from '../ValidationContext';
+
+export function duplicateTypeNameMessage(typeName: string): string;
+
+export function existedTypeNameMessage(typeName: string): string;
+
+/**
+ * Unique type names
+ *
+ * A GraphQL document is only valid if all defined types have unique names.
+ */
+export function UniqueTypeNames(context: SDLValidationContext): ASTVisitor;
diff --git a/tstypes/validation/rules/UniqueVariableNames.d.ts b/tstypes/validation/rules/UniqueVariableNames.d.ts
index ac81c95f9e..0ed9633804 100644
--- a/tstypes/validation/rules/UniqueVariableNames.d.ts
+++ b/tstypes/validation/rules/UniqueVariableNames.d.ts
@@ -1,5 +1,5 @@
-import { ASTValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ASTValidationContext } from '../ValidationContext';
 
 export function duplicateVariableMessage(variableName: string): string;
 
diff --git a/tstypes/validation/rules/ValuesOfCorrectType.d.ts b/tstypes/validation/rules/ValuesOfCorrectType.d.ts
index 3ef5d6d4ed..9b475cf272 100644
--- a/tstypes/validation/rules/ValuesOfCorrectType.d.ts
+++ b/tstypes/validation/rules/ValuesOfCorrectType.d.ts
@@ -1,5 +1,5 @@
-import { ValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ValidationContext } from '../ValidationContext';
 
 export function badValueMessage(
   typeName: string,
@@ -7,6 +7,12 @@ export function badValueMessage(
   message?: string,
 ): string;
 
+export function badEnumValueMessage(
+  typeName: string,
+  valueName: string,
+  suggestedValues: ReadonlyArray<string>,
+): string;
+
 export function requiredFieldMessage(
   typeName: string,
   fieldName: string,
@@ -16,7 +22,7 @@ export function requiredFieldMessage(
 export function unknownFieldMessage(
   typeName: string,
   fieldName: string,
-  message?: string,
+  suggestedFields: ReadonlyArray<string>,
 ): string;
 
 /**
diff --git a/tstypes/validation/rules/VariablesAreInputTypes.d.ts b/tstypes/validation/rules/VariablesAreInputTypes.d.ts
index f5103aea20..ace6fea4b5 100644
--- a/tstypes/validation/rules/VariablesAreInputTypes.d.ts
+++ b/tstypes/validation/rules/VariablesAreInputTypes.d.ts
@@ -1,5 +1,5 @@
-import { ValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ValidationContext } from '../ValidationContext';
 
 export function nonInputTypeOnVarMessage(
   variableName: string,
diff --git a/tstypes/validation/rules/VariablesInAllowedPosition.d.ts b/tstypes/validation/rules/VariablesInAllowedPosition.d.ts
index 84a5dade51..3401c9767f 100644
--- a/tstypes/validation/rules/VariablesInAllowedPosition.d.ts
+++ b/tstypes/validation/rules/VariablesInAllowedPosition.d.ts
@@ -1,5 +1,5 @@
-import { ValidationContext } from '../ValidationContext';
 import { ASTVisitor } from '../../language/visitor';
+import { ValidationContext } from '../ValidationContext';
 
 export function badVarPosMessage(
   varName: string,
diff --git a/tstypes/validation/specifiedRules.d.ts b/tstypes/validation/specifiedRules.d.ts
index 98e9e5eb2b..e26fae8980 100644
--- a/tstypes/validation/specifiedRules.d.ts
+++ b/tstypes/validation/specifiedRules.d.ts
@@ -58,7 +58,10 @@ import { KnownDirectives } from './rules/KnownDirectives';
 import { UniqueDirectivesPerLocation } from './rules/UniqueDirectivesPerLocation';
 
 // Spec Section: "Argument Names"
-import { KnownArgumentNames } from './rules/KnownArgumentNames';
+import {
+  KnownArgumentNames,
+  KnownArgumentNamesOnDirectives, // @internal
+} from './rules/KnownArgumentNames';
 
 // Spec Section: "Argument Uniqueness"
 import { UniqueArgumentNames } from './rules/UniqueArgumentNames';
@@ -67,7 +70,10 @@ import { UniqueArgumentNames } from './rules/UniqueArgumentNames';
 import { ValuesOfCorrectType } from './rules/ValuesOfCorrectType';
 
 // Spec Section: "Argument Optionality"
-import { ProvidedRequiredArguments } from './rules/ProvidedRequiredArguments';
+import {
+  ProvidedRequiredArguments,
+  ProvidedRequiredArgumentsOnDirectives, // @internal
+} from './rules/ProvidedRequiredArguments';
 
 // Spec Section: "All Variable Usages Are Allowed"
 import { VariablesInAllowedPosition } from './rules/VariablesInAllowedPosition';
diff --git a/tstypes/validation/validate.d.ts b/tstypes/validation/validate.d.ts
index 9fe20452a9..e1b80ad3cb 100644
--- a/tstypes/validation/validate.d.ts
+++ b/tstypes/validation/validate.d.ts
@@ -3,6 +3,7 @@ import { DocumentNode } from '../language/ast';
 import { GraphQLSchema } from '../type/schema';
 import { TypeInfo } from '../utilities/TypeInfo';
 import { ValidationRule, SDLValidationRule } from './ValidationContext';
+import Maybe from 'tstypes/tsutils/Maybe';
 
 /**
  * Implements the "Validation" section of the spec.
@@ -25,12 +26,13 @@ export function validate(
   documentAST: DocumentNode,
   rules?: ReadonlyArray<ValidationRule>,
   typeInfo?: TypeInfo,
+  options?: { maxErrors?: number },
 ): ReadonlyArray<GraphQLError>;
 
 // @internal
 export function validateSDL(
   documentAST: DocumentNode,
-  schemaToExtend?: GraphQLSchema | null,
+  schemaToExtend?: Maybe<GraphQLSchema>,
   rules?: ReadonlyArray<SDLValidationRule>,
 ): GraphQLError[];
 
diff --git a/tstypes/version.d.ts b/tstypes/version.d.ts
new file mode 100644
index 0000000000..765329b38b
--- /dev/null
+++ b/tstypes/version.d.ts
@@ -0,0 +1,14 @@
+/**
+ * A string containing the version of the GraphQL.js library
+ */
+export const version: string;
+
+/**
+ * An object containing the components of the GraphQL.js version string
+ */
+export const versionInfo: {
+  major: number;
+  minor: number;
+  patch: number;
+  preReleaseTag: number | null;
+};