diff --git a/packages/eslint-plugin/src/rules/no-empty-function.ts b/packages/eslint-plugin/src/rules/no-empty-function.ts
index 06c04cb4eca..51ec13e3ff0 100644
--- a/packages/eslint-plugin/src/rules/no-empty-function.ts
+++ b/packages/eslint-plugin/src/rules/no-empty-function.ts
@@ -11,6 +11,7 @@ type Options = util.InferOptionsTypeFromRule<typeof baseRule>;
 type MessageIds = util.InferMessageIdsTypeFromRule<typeof baseRule>;
 
 const schema = util.deepMerge(
+  // eslint-disable-next-line @typescript-eslint/no-unsafe-argument -- https://github.com/microsoft/TypeScript/issues/17002
   Array.isArray(baseRule.meta.schema)
     ? baseRule.meta.schema[0]
     : baseRule.meta.schema,
diff --git a/packages/eslint-plugin/src/rules/no-magic-numbers.ts b/packages/eslint-plugin/src/rules/no-magic-numbers.ts
index e63c80686c3..d989ac0eec1 100644
--- a/packages/eslint-plugin/src/rules/no-magic-numbers.ts
+++ b/packages/eslint-plugin/src/rules/no-magic-numbers.ts
@@ -1,18 +1,32 @@
 import {
-  TSESTree,
   AST_NODE_TYPES,
+  TSESTree,
 } from '@typescript-eslint/experimental-utils';
-import { getESLintCoreRule } from '../util/getESLintCoreRule';
 import * as util from '../util';
+import { getESLintCoreRule } from '../util/getESLintCoreRule';
 
 const baseRule = getESLintCoreRule('no-magic-numbers');
 
 type Options = util.InferOptionsTypeFromRule<typeof baseRule>;
 type MessageIds = util.InferMessageIdsTypeFromRule<typeof baseRule>;
 
-const baseRuleSchema = Array.isArray(baseRule.meta.schema)
-  ? baseRule.meta.schema[0]
-  : baseRule.meta.schema;
+// Extend base schema with additional property to ignore TS numeric literal types
+const schema = util.deepMerge(
+  { ...baseRule.meta.schema },
+  {
+    properties: {
+      ignoreNumericLiteralTypes: {
+        type: 'boolean',
+      },
+      ignoreEnums: {
+        type: 'boolean',
+      },
+      ignoreReadonlyClassProperties: {
+        type: 'boolean',
+      },
+    },
+  },
+);
 
 export default util.createRule<Options, MessageIds>({
   name: 'no-magic-numbers',
@@ -23,25 +37,7 @@ export default util.createRule<Options, MessageIds>({
       recommended: false,
       extendsBaseRule: true,
     },
-    hasSuggestions: baseRule.meta.hasSuggestions,
-    // Extend base schema with additional property to ignore TS numeric literal types
-    schema: [
-      {
-        ...baseRuleSchema,
-        properties: {
-          ...baseRuleSchema.properties,
-          ignoreNumericLiteralTypes: {
-            type: 'boolean',
-          },
-          ignoreEnums: {
-            type: 'boolean',
-          },
-          ignoreReadonlyClassProperties: {
-            type: 'boolean',
-          },
-        },
-      },
-    ],
+    schema: [schema],
     messages: baseRule.meta.messages,
   },
   defaultOptions: [
diff --git a/packages/experimental-utils/src/ts-eslint/Rule.ts b/packages/experimental-utils/src/ts-eslint/Rule.ts
index cf3c5b8218b..bac1ef4e353 100644
--- a/packages/experimental-utils/src/ts-eslint/Rule.ts
+++ b/packages/experimental-utils/src/ts-eslint/Rule.ts
@@ -69,15 +69,15 @@ interface RuleMetaData<TMessageIds extends string> {
   /**
    * The name of the rule this rule was replaced by, if it was deprecated.
    */
-  replacedBy?: string[];
+  replacedBy?: readonly string[];
   /**
    * The options schema. Supply an empty array if there are no options.
    */
-  schema: JSONSchema4 | JSONSchema4[];
+  schema: JSONSchema4 | readonly JSONSchema4[];
 }
 
 interface RuleFix {
-  range: AST.Range;
+  range: Readonly<AST.Range>;
   text: string;
 }
 
@@ -87,25 +87,25 @@ interface RuleFixer {
     text: string,
   ): RuleFix;
 
-  insertTextAfterRange(range: AST.Range, text: string): RuleFix;
+  insertTextAfterRange(range: Readonly<AST.Range>, text: string): RuleFix;
 
   insertTextBefore(
     nodeOrToken: TSESTree.Node | TSESTree.Token,
     text: string,
   ): RuleFix;
 
-  insertTextBeforeRange(range: AST.Range, text: string): RuleFix;
+  insertTextBeforeRange(range: Readonly<AST.Range>, text: string): RuleFix;
 
   remove(nodeOrToken: TSESTree.Node | TSESTree.Token): RuleFix;
 
-  removeRange(range: AST.Range): RuleFix;
+  removeRange(range: Readonly<AST.Range>): RuleFix;
 
   replaceText(
     nodeOrToken: TSESTree.Node | TSESTree.Token,
     text: string,
   ): RuleFix;
 
-  replaceTextRange(range: AST.Range, text: string): RuleFix;
+  replaceTextRange(range: Readonly<AST.Range>, text: string): RuleFix;
 }
 
 interface SuggestionReportDescriptor<TMessageIds extends string>
@@ -216,7 +216,7 @@ interface RuleContext<
    * Returns a list of variables declared by the given node.
    * This information can be used to track references to variables.
    */
-  getDeclaredVariables(node: TSESTree.Node): Scope.Variable[];
+  getDeclaredVariables(node: TSESTree.Node): readonly Scope.Variable[];
 
   /**
    * Returns the current working directory passed to Linter.
diff --git a/packages/experimental-utils/src/ts-eslint/RuleTester.ts b/packages/experimental-utils/src/ts-eslint/RuleTester.ts
index 2049d9f90e7..5b748ed36a5 100644
--- a/packages/experimental-utils/src/ts-eslint/RuleTester.ts
+++ b/packages/experimental-utils/src/ts-eslint/RuleTester.ts
@@ -1,7 +1,7 @@
 import { RuleTester as ESLintRuleTester } from 'eslint';
 import { AST_NODE_TYPES, AST_TOKEN_TYPES } from '../ts-estree';
-import { ParserOptions } from './ParserOptions';
 import { Linter } from './Linter';
+import { ParserOptions } from './ParserOptions';
 import {
   RuleCreateFunction,
   RuleModule,
@@ -112,7 +112,7 @@ interface TestCaseError<TMessageIds extends string> {
   /**
    * Reported suggestions.
    */
-  readonly suggestions?: SuggestionOutput<TMessageIds>[] | null;
+  readonly suggestions?: readonly SuggestionOutput<TMessageIds>[] | null;
   /**
    * The type of the reported AST node.
    */