diff --git a/src/type/__tests__/predicate-test.js b/src/type/__tests__/predicate-test.js
index 7e655a7bab0..2a5f885b623 100644
--- a/src/type/__tests__/predicate-test.js
+++ b/src/type/__tests__/predicate-test.js
@@ -573,77 +573,87 @@ describe('Type predicates', () => {
   });
 
   describe('isRequiredArgument', () => {
-    it('returns true for required arguments', () => {
-      const requiredArg = {
+    function buildArg(config) {
+      return {
         name: 'someArg',
-        type: GraphQLNonNull(GraphQLString),
+        description: undefined,
+        defaultValue: undefined,
+        astNode: undefined,
+        ...config,
       };
+    }
+
+    it('returns true for required arguments', () => {
+      const requiredArg = buildArg({
+        type: GraphQLNonNull(GraphQLString),
+      });
       expect(isRequiredArgument(requiredArg)).to.equal(true);
     });
 
     it('returns false for optional arguments', () => {
-      const optArg1 = {
-        name: 'someArg',
+      const optArg1 = buildArg({
         type: GraphQLString,
-      };
+      });
       expect(isRequiredArgument(optArg1)).to.equal(false);
 
-      const optArg2 = {
-        name: 'someArg',
+      const optArg2 = buildArg({
         type: GraphQLString,
         defaultValue: null,
-      };
+      });
       expect(isRequiredArgument(optArg2)).to.equal(false);
 
-      const optArg3 = {
-        name: 'someArg',
+      const optArg3 = buildArg({
         type: GraphQLList(GraphQLNonNull(GraphQLString)),
-      };
+      });
       expect(isRequiredArgument(optArg3)).to.equal(false);
 
-      const optArg4 = {
-        name: 'someArg',
+      const optArg4 = buildArg({
         type: GraphQLNonNull(GraphQLString),
         defaultValue: 'default',
-      };
+      });
       expect(isRequiredArgument(optArg4)).to.equal(false);
     });
   });
 
   describe('isRequiredInputField', () => {
+    function buildInputField(config) {
+      return {
+        name: 'someInputField',
+        description: undefined,
+        defaultValue: undefined,
+        astNode: undefined,
+        ...config,
+      };
+    }
+
     it('returns true for required input field', () => {
-      const requiredField = {
-        name: 'someField',
+      const requiredField = buildInputField({
         type: GraphQLNonNull(GraphQLString),
-      };
+      });
       expect(isRequiredInputField(requiredField)).to.equal(true);
     });
 
     it('returns false for optional input field', () => {
-      const optField1 = {
-        name: 'someField',
+      const optField1 = buildInputField({
         type: GraphQLString,
-      };
+      });
       expect(isRequiredInputField(optField1)).to.equal(false);
 
-      const optField2 = {
-        name: 'someField',
+      const optField2 = buildInputField({
         type: GraphQLString,
         defaultValue: null,
-      };
+      });
       expect(isRequiredInputField(optField2)).to.equal(false);
 
-      const optField3 = {
-        name: 'someField',
+      const optField3 = buildInputField({
         type: GraphQLList(GraphQLNonNull(GraphQLString)),
-      };
+      });
       expect(isRequiredInputField(optField3)).to.equal(false);
 
-      const optField4 = {
-        name: 'someField',
+      const optField4 = buildInputField({
         type: GraphQLNonNull(GraphQLString),
         defaultValue: 'default',
-      };
+      });
       expect(isRequiredInputField(optField4)).to.equal(false);
     });
   });
diff --git a/src/type/definition.js b/src/type/definition.js
index ce151b6d899..f2105c049f3 100644
--- a/src/type/definition.js
+++ b/src/type/definition.js
@@ -909,16 +909,16 @@ export type GraphQLField<
   resolve?: GraphQLFieldResolver<TSource, TContext, TArgs>,
   subscribe?: GraphQLFieldResolver<TSource, TContext, TArgs>,
   isDeprecated?: boolean,
-  deprecationReason?: ?string,
-  astNode?: ?FieldDefinitionNode,
+  deprecationReason: ?string,
+  astNode: ?FieldDefinitionNode,
 |};
 
 export type GraphQLArgument = {|
   name: string,
-  description?: ?string,
+  description: ?string,
   type: GraphQLInputType,
   defaultValue?: mixed,
-  astNode?: ?InputValueDefinitionNode,
+  astNode: ?InputValueDefinitionNode,
 |};
 
 export function isRequiredArgument(arg: GraphQLArgument): boolean %checks {
@@ -1286,7 +1286,7 @@ export type GraphQLEnumValue /* <T> */ = {|
   value: any /* T */,
   isDeprecated?: boolean,
   deprecationReason: ?string,
-  astNode?: ?EnumValueDefinitionNode,
+  astNode: ?EnumValueDefinitionNode,
 |};
 
 /**
@@ -1407,10 +1407,10 @@ export type GraphQLInputFieldConfigMap = ObjMap<GraphQLInputFieldConfig>;
 
 export type GraphQLInputField = {|
   name: string,
-  description?: ?string,
+  description: ?string,
   type: GraphQLInputType,
   defaultValue?: mixed,
-  astNode?: ?InputValueDefinitionNode,
+  astNode: ?InputValueDefinitionNode,
 |};
 
 export function isRequiredInputField(
diff --git a/src/type/introspection.js b/src/type/introspection.js
index eff1e0c42e3..3f85aad6a90 100644
--- a/src/type/introspection.js
+++ b/src/type/introspection.js
@@ -438,14 +438,25 @@ export const SchemaMetaFieldDef: GraphQLField<mixed, mixed> = {
   description: 'Access the current type schema of this server.',
   args: [],
   resolve: (source, args, context, { schema }) => schema,
+  deprecationReason: undefined,
+  astNode: undefined,
 };
 
 export const TypeMetaFieldDef: GraphQLField<mixed, mixed> = {
   name: '__type',
   type: __Type,
   description: 'Request the type information of a single type.',
-  args: [{ name: 'name', type: GraphQLNonNull(GraphQLString) }],
+  args: [
+    {
+      name: 'name',
+      description: undefined,
+      type: GraphQLNonNull(GraphQLString),
+      astNode: undefined,
+    },
+  ],
   resolve: (source, { name }, context, { schema }) => schema.getType(name),
+  deprecationReason: undefined,
+  astNode: undefined,
 };
 
 export const TypeNameMetaFieldDef: GraphQLField<mixed, mixed> = {
@@ -454,6 +465,8 @@ export const TypeNameMetaFieldDef: GraphQLField<mixed, mixed> = {
   description: 'The name of the current Object type at runtime.',
   args: [],
   resolve: (source, args, context, { parentType }) => parentType.name,
+  deprecationReason: undefined,
+  astNode: undefined,
 };
 
 export const introspectionTypes = Object.freeze([