feat(anthropic): web search server tool

js/plugins/anthropic/README.md

@@ -95,6 +95,21 @@ The beta API surface provides access to experimental features, but some server-m
 
 Note that `server_tool_use` and `web_search_tool_result` ARE supported and work with both stable and beta APIs.
 
+### Web Search Tool
+
+You can use Anthropic's web search tool by defining the tool in the prompt.
+
+```typescript
+const response = await ai.generate({
+  prompt: 'What is the weather in Tokyo?',
+  config: {
+    tools: [{ type: 'web_search_20250305', name: 'web_search' }],
+  },
+});
+```
+
+By default, the tool will only be used if it matches the user's prompt. You can override this behavior by modifying the `tool_choice` config option.
+
 ### Within a flow
 
 ```typescript

js/plugins/anthropic/src/runner/converters/beta.ts

@@ -35,7 +35,6 @@ export function betaServerToolUseBlockToPart(block: {
     ? `${block.server_name}/${baseName}`
     : baseName;
   return {
-    text: `[Anthropic server tool ${serverToolName}] input: ${JSON.stringify(block.input)}`,
     metadata: {
       anthropicServerToolUse: {
         id: block.id,

js/plugins/anthropic/src/runner/converters/shared.ts

@@ -76,7 +76,6 @@ export function webSearchToolResultBlockToPart(block: {
   content: unknown;
 }): Part {
   return {
-    text: `[Anthropic server tool result ${block.tool_use_id}] ${JSON.stringify(block.content)}`,
     metadata: {
       anthropicServerToolResult: {
         type: 'web_search_tool_result',

js/plugins/anthropic/src/runner/converters/stable.ts

@@ -30,7 +30,6 @@ export function serverToolUseBlockToPart(block: {
   input: unknown;
 }): Part {
   return {
-    text: `[Anthropic server tool ${block.name}] input: ${JSON.stringify(block.input)}`,
     metadata: {
       anthropicServerToolUse: {
         id: block.id,

js/plugins/anthropic/tests/beta_runner_test.ts

@@ -320,7 +320,6 @@ describe('BetaRunner', () => {
     } as any;
     const toolPart = exposed.toGenkitPart(serverToolEvent);
     assert.deepStrictEqual(toolPart, {
-      text: '[Anthropic server tool srv/myTool] input: {"foo":"bar"}',
       metadata: {
         anthropicServerToolUse: {
           id: 'toolu_test',
@@ -765,7 +764,6 @@ describe('BetaRunner', () => {
       server_name: 'srv',
     });
     assert.deepStrictEqual(serverToolPart, {
-      text: '[Anthropic server tool srv/serverTool] input: {"arg":"value"}',
       metadata: {
         anthropicServerToolUse: {
           id: 'srv_tool_1',

js/testapps/anthropic/README.md

@@ -42,6 +42,7 @@ src/
 - `pnpm run dev:stable:webp` – Start Dev UI for WEBP image handling demo.
 - `pnpm run dev:stable:pdf` – Start Dev UI for PDF document processing demo.
 - `pnpm run dev:stable:vision` – Start Dev UI for image/vision analysis demo.
+- `pnpm run dev:stable:web-search-tool` – Start Dev UI for web search tool demo.
 
 ## Flows
 
@@ -72,4 +73,8 @@ Each source file defines flows that can be invoked from the Dev UI or the Genkit
 - `stable-vision-base64` – Analyze an image from a local file (base64 encoded)
 - `stable-vision-conversation` – Multi-turn conversation about an image
 
+### Web Search Tool
+- `stable-web-search-tool` – Use the web search tool to find the weather in Tokyo
+- `stable-web-search-tool-stream` – Streaming response with web search tool
+
 Example: `genkit flow:run anthropic-stable-hello`

js/testapps/anthropic/package.json

@@ -19,6 +19,7 @@
     "dev:stable:pdf": "genkit start -- npx tsx --watch src/stable/pdf.ts",
     "dev:stable:tools": "genkit start -- npx tsx --watch src/stable/tools.ts",
     "dev:stable:vision": "genkit start -- npx tsx --watch src/stable/vision.ts",
+    "dev:stable:web-search-tool": "genkit start -- npx tsx --watch src/stable/web-search-tool.ts",
     "genkit:dev": "cross-env GENKIT_ENV=dev npm run dev:stable",
     "genkit:start": "cross-env GENKIT_ENV=dev genkit start -- tsx --watch src/stable/basic.ts",
     "dev": "export GENKIT_RUNTIME_ID=$(openssl rand -hex 8) && node lib/stable/basic.js 2>&1"

js/testapps/anthropic/src/stable/web-search-tool.ts

@@ -0,0 +1,70 @@
+/**
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { anthropic } from '@genkit-ai/anthropic';
+import { genkit } from 'genkit';
+
+const ai = genkit({
+  plugins: [
+    // Configure the plugin with environment-driven API key
+    anthropic(),
+  ],
+});
+
+ai.defineFlow('anthropic-stable-web-search-tool', async () => {
+  const { text } = await ai.generate({
+    model: anthropic.model('claude-sonnet-4-5'),
+    prompt: 'What is the weather in Tokyo?',
+    config: {
+      tools: [
+        {
+          type: 'web_search_20250305',
+          name: 'web_search',
+        },
+      ],
+    },
+  });
+
+  return text;
+});
+
+ai.defineFlow(
+  'anthropic-stable-web-search-tool-stream',
+  async (_, { sendChunk }) => {
+    const { stream } = ai.generateStream({
+      model: anthropic.model('claude-sonnet-4-5'),
+      prompt: 'What is the weather in Tokyo?',
+      config: {
+        tools: [
+          {
+            type: 'web_search_20250305',
+            name: 'web_search',
+          },
+        ],
+      },
+    });
+
+    let response = '';
+    for await (const chunk of stream) {
+      if (chunk.text) {
+        response += chunk.text;
+        sendChunk(chunk.text);
+      }
+    }
+
+    return response;
+  }
+);