From 78032a641881b229cd8a00c07be63b09233d9af0 Mon Sep 17 00:00:00 2001
From: snowingfox <1503401882@qq.com>
Date: Wed, 12 Aug 2026 03:52:55 +0000
Subject: [PATCH] fix(core): preserve per-tool argument type inference in
 provideExperimentalWebMcpTools

Fixes #70125
---
 goldens/public-api/core/index.api.md          |  2 +-
 packages/core/src/webmcp/provide_tools.ts     |  6 ++-
 .../core/test/strict_types/mcp_tools_spec.ts  | 54 +++++++++++++++++++
 3 files changed, 59 insertions(+), 3 deletions(-)
 create mode 100644 packages/core/test/strict_types/mcp_tools_spec.ts

diff --git a/goldens/public-api/core/index.api.md b/goldens/public-api/core/index.api.md
index d1002e1ec71a..0e9d31a239ee 100644
--- a/goldens/public-api/core/index.api.md
+++ b/goldens/public-api/core/index.api.md
@@ -1502,7 +1502,7 @@ export function provideCheckNoChangesConfig(options: {
 export function provideEnvironmentInitializer(initializerFn: () => void): EnvironmentProviders;
 
 // @public
-export function provideExperimentalWebMcpTools<const InputSchema extends JsonSchemaForInference>(tools: WebMcpToolDescriptor<InputSchema>[]): EnvironmentProviders;
+export function provideExperimentalWebMcpTools<const InputSchemas extends readonly JsonSchemaForInference[]>(tools: { [K in keyof InputSchemas]: WebMcpToolDescriptor<InputSchemas[K]>; }): EnvironmentProviders;
 
 // @public
 export function provideIdleServiceWith(useExisting: AbstractType<IdleService> | InjectionToken<IdleService>): EnvironmentProviders;
diff --git a/packages/core/src/webmcp/provide_tools.ts b/packages/core/src/webmcp/provide_tools.ts
index 0047f8a9a996..a7cf6084e436 100644
--- a/packages/core/src/webmcp/provide_tools.ts
+++ b/packages/core/src/webmcp/provide_tools.ts
@@ -26,8 +26,10 @@ import type {ToolDescriptor} from './types';
  *     or route providers.
  * @experimental
  */
-export function provideExperimentalWebMcpTools<const InputSchema extends JsonSchemaForInference>(
-  tools: ToolDescriptor<InputSchema>[],
+export function provideExperimentalWebMcpTools<
+  const InputSchemas extends readonly JsonSchemaForInference[],
+>(
+  tools: {[K in keyof InputSchemas]: ToolDescriptor<InputSchemas[K]>},
 ): EnvironmentProviders {
   return makeEnvironmentProviders([
     provideEnvironmentInitializer(() => {
diff --git a/packages/core/test/strict_types/mcp_tools_spec.ts b/packages/core/test/strict_types/mcp_tools_spec.ts
new file mode 100644
index 000000000000..0b7ccec656ac
--- /dev/null
+++ b/packages/core/test/strict_types/mcp_tools_spec.ts
@@ -0,0 +1,54 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.dev/license
+ */
+
+import {provideExperimentalWebMcpTools} from '../../src/webmcp/provide_tools';
+
+describe('provideExperimentalWebMcpTools', () => {
+  // Regression test for https://github.com/angular/angular/issues/70125
+  //
+  // Each tool passed to `provideExperimentalWebMcpTools` must infer its own
+  // argument types from its own `inputSchema`. Previously the function inferred
+  // a single shared `InputSchema` for the whole array, so heterogeneous tools
+  // lost their `execute` argument types (each `args` was widened to
+  // `Record<string, unknown>`), making the `arg1`/`arg2` accesses below type
+  // errors. This file intentionally fails to compile on the unfixed signature.
+  it('should preserve per-tool argument types for heterogeneous input schemas', () => {
+    provideExperimentalWebMcpTools([
+      {
+        name: 'tool1',
+        description: 'Tool #1',
+        inputSchema: {
+          type: 'object',
+          properties: {
+            arg1: {type: 'number'},
+          },
+          required: ['arg1'],
+        },
+        execute: (args) => {
+          const arg1 = args.arg1; // must be inferred as `number`
+          return `arg1 number value is ${arg1.toFixed()}`;
+        },
+      },
+      {
+        name: 'tool2',
+        description: 'Tool #2',
+        inputSchema: {
+          type: 'object',
+          properties: {
+            arg2: {type: 'string'},
+          },
+          required: ['arg2'],
+        },
+        execute: (args) => {
+          const arg2 = args.arg2; // must be inferred as `string`
+          return `arg2 string value is ${arg2.trim()}`;
+        },
+      },
+    ]);
+  });
+});