From e31370283814140cf1cd4a54e48b3dd49b08682e Mon Sep 17 00:00:00 2001
From: Natallia Harshunova <nharshunova@chromium.org>
Date: Tue, 13 Jan 2026 16:06:07 +0000
Subject: [PATCH 1/9] Implement install_extension command

---
 src/McpContext.ts           |  4 +++
 src/cli.ts                  |  7 ++++++
 src/main.ts                 | 49 ++++++++++++++++++++++---------------
 src/tools/ToolDefinition.ts |  1 +
 src/tools/categories.ts     |  2 ++
 src/tools/extension.ts      | 35 ++++++++++++++++++++++++++
 src/tools/tools.ts          |  2 ++
 7 files changed, 80 insertions(+), 20 deletions(-)
 create mode 100644 src/tools/extension.ts

diff --git a/src/McpContext.ts b/src/McpContext.ts
index aa848493d..05bf6f16f 100644
--- a/src/McpContext.ts
+++ b/src/McpContext.ts
@@ -690,4 +690,8 @@ export class McpContext implements Context {
     });
     await this.#networkCollector.init(await this.browser.pages());
   }
+
+  async installExtension(path: string): Promise<string> {
+    return this.browser.installExtension(path);
+  }
 }
diff --git a/src/cli.ts b/src/cli.ts
index 24d5efba2..0e9dcf3ea 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -198,6 +198,12 @@ export const cliOptions = {
     default: true,
     describe: 'Set to false to exclude tools related to network.',
   },
+  categoryExtension: {
+    type: 'boolean',
+    default: true,
+    hidden: true,
+    describe: 'Set to false to exclude tools related to extensions.',
+  },
   usageStatistics: {
     type: 'boolean',
     // Marked as `false` until the feature is ready to be enabled by default.
@@ -261,6 +267,7 @@ export function parseArguments(version: string, argv = process.argv) {
         'Disable tools in the performance category',
       ],
       ['$0 --no-category-network', 'Disable tools in the network category'],
+      ['$0 --no-category-extension', 'Disable tools in the extension category'],
       [
         '$0 --user-data-dir=/tmp/user-data-dir',
         'Use a custom user data directory',
diff --git a/src/main.ts b/src/main.ts
index a4976c0fb..0aedf8dcd 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -64,6 +64,9 @@ async function getContext(): Promise<McpContext> {
   const ignoreDefaultChromeArgs: string[] = (
     args.ignoreDefaultChromeArg ?? []
   ).map(String);
+  if (args.categoryExtension) {
+    chromeArgs.push('--enable-unsafe-extension-debugging');
+  }
   if (args.proxyServer) {
     chromeArgs.push(`--proxy-server=${args.proxyServer}`);
   }
@@ -71,27 +74,27 @@ async function getContext(): Promise<McpContext> {
   const browser =
     args.browserUrl || args.wsEndpoint || args.autoConnect
       ? await ensureBrowserConnected({
-          browserURL: args.browserUrl,
-          wsEndpoint: args.wsEndpoint,
-          wsHeaders: args.wsHeaders,
-          // Important: only pass channel, if autoConnect is true.
-          channel: args.autoConnect ? (args.channel as Channel) : undefined,
-          userDataDir: args.userDataDir,
-          devtools,
-        })
+        browserURL: args.browserUrl,
+        wsEndpoint: args.wsEndpoint,
+        wsHeaders: args.wsHeaders,
+        // Important: only pass channel, if autoConnect is true.
+        channel: args.autoConnect ? (args.channel as Channel) : undefined,
+        userDataDir: args.userDataDir,
+        devtools,
+      })
       : await ensureBrowserLaunched({
-          headless: args.headless,
-          executablePath: args.executablePath,
-          channel: args.channel as Channel,
-          isolated: args.isolated ?? false,
-          userDataDir: args.userDataDir,
-          logFile,
-          viewport: args.viewport,
-          chromeArgs,
-          ignoreDefaultChromeArgs,
-          acceptInsecureCerts: args.acceptInsecureCerts,
-          devtools,
-        });
+        headless: args.headless,
+        executablePath: args.executablePath,
+        channel: args.channel as Channel,
+        isolated: args.isolated ?? false,
+        userDataDir: args.userDataDir,
+        logFile,
+        viewport: args.viewport,
+        chromeArgs,
+        ignoreDefaultChromeArgs,
+        acceptInsecureCerts: args.acceptInsecureCerts,
+        devtools,
+      });
 
   if (context?.browser !== browser) {
     context = await McpContext.from(browser, logger, {
@@ -139,6 +142,12 @@ function registerTool(tool: ToolDefinition): void {
   ) {
     return;
   }
+  if (
+    tool.annotations.category === ToolCategory.EXTENSION &&
+    args.categoryExtension === false
+  ) {
+    return;
+  }
   if (
     tool.annotations.conditions?.includes('computerVision') &&
     !args.experimentalVision
diff --git a/src/tools/ToolDefinition.ts b/src/tools/ToolDefinition.ts
index feae3c7be..f2b699021 100644
--- a/src/tools/ToolDefinition.ts
+++ b/src/tools/ToolDefinition.ts
@@ -121,6 +121,7 @@ export type Context = Readonly<{
    * Returns a reqid for a cdpRequestId.
    */
   resolveCdpElementId(cdpBackendNodeId: number): string | undefined;
+  installExtension(path: string): Promise<string>;
 }>;
 
 export function defineTool<Schema extends zod.ZodRawShape>(
diff --git a/src/tools/categories.ts b/src/tools/categories.ts
index f27a80361..161ff55b1 100644
--- a/src/tools/categories.ts
+++ b/src/tools/categories.ts
@@ -11,6 +11,7 @@ export enum ToolCategory {
   PERFORMANCE = 'performance',
   NETWORK = 'network',
   DEBUGGING = 'debugging',
+  EXTENSION = 'extension',
 }
 
 export const labels = {
@@ -20,4 +21,5 @@ export const labels = {
   [ToolCategory.PERFORMANCE]: 'Performance',
   [ToolCategory.NETWORK]: 'Network',
   [ToolCategory.DEBUGGING]: 'Debugging',
+  [ToolCategory.EXTENSION]: 'Extensions',
 };
diff --git a/src/tools/extension.ts b/src/tools/extension.ts
new file mode 100644
index 000000000..f23d490a7
--- /dev/null
+++ b/src/tools/extension.ts
@@ -0,0 +1,35 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { logger } from '../logger.js';
+import { zod } from '../third_party/index.js';
+
+import { ToolCategory } from './categories.js';
+import { defineTool } from './ToolDefinition.js';
+
+export const installExtension = defineTool({
+  name: 'install_extension',
+  description: 'Installs a Chrome extension from the given path.',
+  annotations: {
+    category: ToolCategory.EXTENSION,
+    readOnlyHint: false,
+  },
+  schema: {
+    path: zod
+      .string()
+      .describe('Absolute path to the unpacked extension folder.'),
+  },
+  handler: async (request, response, context) => {
+    const { path } = request.params;
+    try {
+      const id = await context.installExtension(path);
+      response.appendResponseLine(`Extension installed: ${id}`);
+    } catch (error) {
+      logger('Extension installation error: ', error);
+      throw error;
+    }
+  },
+});
diff --git a/src/tools/tools.ts b/src/tools/tools.ts
index 227fb0d42..b670226ab 100644
--- a/src/tools/tools.ts
+++ b/src/tools/tools.ts
@@ -5,6 +5,7 @@
  */
 import * as consoleTools from './console.js';
 import * as emulationTools from './emulation.js';
+import * as extensionTools from './extension.js';
 import * as inputTools from './input.js';
 import * as networkTools from './network.js';
 import * as pagesTools from './pages.js';
@@ -17,6 +18,7 @@ import type {ToolDefinition} from './ToolDefinition.js';
 const tools = [
   ...Object.values(consoleTools),
   ...Object.values(emulationTools),
+  ...Object.values(extensionTools),
   ...Object.values(inputTools),
   ...Object.values(networkTools),
   ...Object.values(pagesTools),

From aa0875892077f0e517f1e34bb2bd15635973d0fa Mon Sep 17 00:00:00 2001
From: Natallia Harshunova <nharshunova@chromium.org>
Date: Wed, 14 Jan 2026 17:23:34 +0000
Subject: [PATCH 2/9] Implement install_extension command Fix pr comments

---
 README.md                                 |  2 +
 docs/tool-reference.md                    | 14 +++++
 src/browser.ts                            |  1 +
 src/cli.ts                                |  5 +-
 src/main.ts                               | 47 ++++++++-------
 src/tools/categories.ts                   |  4 +-
 src/tools/{extension.ts => extensions.ts} | 14 ++---
 src/tools/tools.ts                        |  2 +-
 tests/cli.test.ts                         |  2 +
 tests/index.test.ts                       | 14 +++++
 tests/tools/extension.test.ts             | 68 ++++++++++++++++++++++
 tests/tools/extensions.test.ts            | 69 +++++++++++++++++++++++
 tests/utils.ts                            |  1 +
 13 files changed, 205 insertions(+), 38 deletions(-)
 rename src/tools/{extension.ts => extensions.ts} (65%)
 create mode 100644 tests/tools/extension.test.ts
 create mode 100644 tests/tools/extensions.test.ts

diff --git a/README.md b/README.md
index 1f663eb60..8b1681af9 100644
--- a/README.md
+++ b/README.md
@@ -360,6 +360,8 @@ If you run into any issues, checkout our [troubleshooting guide](./docs/troubles
   - [`list_console_messages`](docs/tool-reference.md#list_console_messages)
   - [`take_screenshot`](docs/tool-reference.md#take_screenshot)
   - [`take_snapshot`](docs/tool-reference.md#take_snapshot)
+- **Extensions** (1 tools)
+  - [`install_extension`](docs/tool-reference.md#install_extension)
 
 <!-- END AUTO GENERATED TOOLS -->
 
diff --git a/docs/tool-reference.md b/docs/tool-reference.md
index ac8ab1f53..60895c56b 100644
--- a/docs/tool-reference.md
+++ b/docs/tool-reference.md
@@ -34,6 +34,8 @@
   - [`list_console_messages`](#list_console_messages)
   - [`take_screenshot`](#take_screenshot)
   - [`take_snapshot`](#take_snapshot)
+- **[Extensions](#extensions)** (1 tools)
+  - [`install_extension`](#install_extension)
 
 ## Input automation
 
@@ -345,3 +347,15 @@ in the DevTools Elements panel (if any).
 - **verbose** (boolean) _(optional)_: Whether to include all possible information available in the full a11y tree. Default is false.
 
 ---
+
+## Extensions
+
+### `install_extension`
+
+**Description:** Installs a Chrome extension from the given path.
+
+**Parameters:**
+
+- **path** (string) **(required)**: Absolute path to the unpacked extension folder.
+
+---
diff --git a/src/browser.ts b/src/browser.ts
index 628007f6b..71e9376ca 100644
--- a/src/browser.ts
+++ b/src/browser.ts
@@ -201,6 +201,7 @@ export async function launch(options: McpLaunchOptions): Promise<Browser> {
       ignoreDefaultArgs: ignoreDefaultArgs,
       acceptInsecureCerts: options.acceptInsecureCerts,
       handleDevToolsAsPage: true,
+      enableExtensions: true,
     });
     if (options.logFile) {
       // FIXME: we are probably subscribing too late to catch startup logs. We
diff --git a/src/cli.ts b/src/cli.ts
index 0e9dcf3ea..e617c31eb 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -198,9 +198,9 @@ export const cliOptions = {
     default: true,
     describe: 'Set to false to exclude tools related to network.',
   },
-  categoryExtension: {
+  categoryExtensions: {
     type: 'boolean',
-    default: true,
+    default: false,
     hidden: true,
     describe: 'Set to false to exclude tools related to extensions.',
   },
@@ -267,7 +267,6 @@ export function parseArguments(version: string, argv = process.argv) {
         'Disable tools in the performance category',
       ],
       ['$0 --no-category-network', 'Disable tools in the network category'],
-      ['$0 --no-category-extension', 'Disable tools in the extension category'],
       [
         '$0 --user-data-dir=/tmp/user-data-dir',
         'Use a custom user data directory',
diff --git a/src/main.ts b/src/main.ts
index 0aedf8dcd..665dd1cf7 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -64,9 +64,6 @@ async function getContext(): Promise<McpContext> {
   const ignoreDefaultChromeArgs: string[] = (
     args.ignoreDefaultChromeArg ?? []
   ).map(String);
-  if (args.categoryExtension) {
-    chromeArgs.push('--enable-unsafe-extension-debugging');
-  }
   if (args.proxyServer) {
     chromeArgs.push(`--proxy-server=${args.proxyServer}`);
   }
@@ -74,27 +71,27 @@ async function getContext(): Promise<McpContext> {
   const browser =
     args.browserUrl || args.wsEndpoint || args.autoConnect
       ? await ensureBrowserConnected({
-        browserURL: args.browserUrl,
-        wsEndpoint: args.wsEndpoint,
-        wsHeaders: args.wsHeaders,
-        // Important: only pass channel, if autoConnect is true.
-        channel: args.autoConnect ? (args.channel as Channel) : undefined,
-        userDataDir: args.userDataDir,
-        devtools,
-      })
+          browserURL: args.browserUrl,
+          wsEndpoint: args.wsEndpoint,
+          wsHeaders: args.wsHeaders,
+          // Important: only pass channel, if autoConnect is true.
+          channel: args.autoConnect ? (args.channel as Channel) : undefined,
+          userDataDir: args.userDataDir,
+          devtools,
+        })
       : await ensureBrowserLaunched({
-        headless: args.headless,
-        executablePath: args.executablePath,
-        channel: args.channel as Channel,
-        isolated: args.isolated ?? false,
-        userDataDir: args.userDataDir,
-        logFile,
-        viewport: args.viewport,
-        chromeArgs,
-        ignoreDefaultChromeArgs,
-        acceptInsecureCerts: args.acceptInsecureCerts,
-        devtools,
-      });
+          headless: args.headless,
+          executablePath: args.executablePath,
+          channel: args.channel as Channel,
+          isolated: args.isolated ?? false,
+          userDataDir: args.userDataDir,
+          logFile,
+          viewport: args.viewport,
+          chromeArgs,
+          ignoreDefaultChromeArgs,
+          acceptInsecureCerts: args.acceptInsecureCerts,
+          devtools,
+        });
 
   if (context?.browser !== browser) {
     context = await McpContext.from(browser, logger, {
@@ -143,8 +140,8 @@ function registerTool(tool: ToolDefinition): void {
     return;
   }
   if (
-    tool.annotations.category === ToolCategory.EXTENSION &&
-    args.categoryExtension === false
+    tool.annotations.category === ToolCategory.EXTENSIONS &&
+    args.categoryExtensions === false
   ) {
     return;
   }
diff --git a/src/tools/categories.ts b/src/tools/categories.ts
index 161ff55b1..9e3512689 100644
--- a/src/tools/categories.ts
+++ b/src/tools/categories.ts
@@ -11,7 +11,7 @@ export enum ToolCategory {
   PERFORMANCE = 'performance',
   NETWORK = 'network',
   DEBUGGING = 'debugging',
-  EXTENSION = 'extension',
+  EXTENSIONS = 'extensions',
 }
 
 export const labels = {
@@ -21,5 +21,5 @@ export const labels = {
   [ToolCategory.PERFORMANCE]: 'Performance',
   [ToolCategory.NETWORK]: 'Network',
   [ToolCategory.DEBUGGING]: 'Debugging',
-  [ToolCategory.EXTENSION]: 'Extensions',
+  [ToolCategory.EXTENSIONS]: 'Extensions',
 };
diff --git a/src/tools/extension.ts b/src/tools/extensions.ts
similarity index 65%
rename from src/tools/extension.ts
rename to src/tools/extensions.ts
index f23d490a7..25537bd2a 100644
--- a/src/tools/extension.ts
+++ b/src/tools/extensions.ts
@@ -4,17 +4,17 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import { logger } from '../logger.js';
-import { zod } from '../third_party/index.js';
+import {logger} from '../logger.js';
+import {zod} from '../third_party/index.js';
 
-import { ToolCategory } from './categories.js';
-import { defineTool } from './ToolDefinition.js';
+import {ToolCategory} from './categories.js';
+import {defineTool} from './ToolDefinition.js';
 
 export const installExtension = defineTool({
   name: 'install_extension',
   description: 'Installs a Chrome extension from the given path.',
   annotations: {
-    category: ToolCategory.EXTENSION,
+    category: ToolCategory.EXTENSIONS,
     readOnlyHint: false,
   },
   schema: {
@@ -23,10 +23,10 @@ export const installExtension = defineTool({
       .describe('Absolute path to the unpacked extension folder.'),
   },
   handler: async (request, response, context) => {
-    const { path } = request.params;
+    const {path} = request.params;
     try {
       const id = await context.installExtension(path);
-      response.appendResponseLine(`Extension installed: ${id}`);
+      response.appendResponseLine(`Extension installed. Id: ${id}`);
     } catch (error) {
       logger('Extension installation error: ', error);
       throw error;
diff --git a/src/tools/tools.ts b/src/tools/tools.ts
index b670226ab..140edf61c 100644
--- a/src/tools/tools.ts
+++ b/src/tools/tools.ts
@@ -5,7 +5,7 @@
  */
 import * as consoleTools from './console.js';
 import * as emulationTools from './emulation.js';
-import * as extensionTools from './extension.js';
+import * as extensionTools from './extensions.js';
 import * as inputTools from './input.js';
 import * as networkTools from './network.js';
 import * as pagesTools from './pages.js';
diff --git a/tests/cli.test.ts b/tests/cli.test.ts
index ccbeac8cd..add84e328 100644
--- a/tests/cli.test.ts
+++ b/tests/cli.test.ts
@@ -15,6 +15,8 @@ describe('cli args parsing', () => {
     categoryEmulation: true,
     'category-performance': true,
     categoryPerformance: true,
+    'category-extensions': false,
+    categoryExtensions: false,
     'category-network': true,
     categoryNetwork: true,
     'auto-connect': undefined,
diff --git a/tests/index.test.ts b/tests/index.test.ts
index 021567a80..0490af334 100644
--- a/tests/index.test.ts
+++ b/tests/index.test.ts
@@ -108,6 +108,9 @@ describe('e2e', () => {
             ) {
               continue;
             }
+            if (maybeTool.name === 'install_extension') {
+              continue;
+            }
             definedNames.push(maybeTool.name);
           }
         }
@@ -117,6 +120,17 @@ describe('e2e', () => {
     });
   });
 
+  it('has experimental extensions tools', async () => {
+    await withClient(
+      async client => {
+        const {tools} = await client.listTools();
+        const clickAt = tools.find(t => t.name === 'install_extension');
+        assert.ok(clickAt);
+      },
+      ['--category-extensions'],
+    );
+  });
+
   it('has experimental vision tools', async () => {
     await withClient(
       async client => {
diff --git a/tests/tools/extension.test.ts b/tests/tools/extension.test.ts
new file mode 100644
index 000000000..4ccd508c4
--- /dev/null
+++ b/tests/tools/extension.test.ts
@@ -0,0 +1,68 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import assert from 'node:assert';
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+import {describe, it, after} from 'node:test';
+
+import {installExtension} from '../../src/tools/extensions.js';
+import {withMcpContext} from '../utils.js';
+
+describe('extension', () => {
+  let tmpDir: string;
+
+  it('installs an extension and verifies it is listed in chrome://extensions', async () => {
+    tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'extension-test-'));
+    fs.writeFileSync(
+      path.join(tmpDir, 'manifest.json'),
+      JSON.stringify({
+        manifest_version: 3,
+        name: 'Test Extension',
+        version: '1.0',
+        action: {
+          default_popup: 'popup.html',
+        },
+      }),
+    );
+    fs.writeFileSync(
+      path.join(tmpDir, 'popup.html'),
+      '<!DOCTYPE html><html><body><h1>Test Popup</h1></body></html>',
+    );
+
+    await withMcpContext(async (response, context) => {
+      await installExtension.handler(
+        {params: {path: tmpDir}},
+        response,
+        context,
+      );
+
+      const responseLine = response.responseLines[0];
+      assert.ok(responseLine, 'Response should not be empty');
+      const match = responseLine.match(/Extension installed\. Id: (.+)/);
+      const extensionId = match ? match[1] : null;
+      assert.ok(extensionId, 'Response should contain a valid key');
+
+      const page = context.getSelectedPage();
+      await page.goto('chrome://extensions');
+
+      const element = await page.waitForSelector(
+        `extensions-manager >>> extensions-item[id="${extensionId}"]`,
+      );
+      assert.ok(
+        element,
+        `Extension with ID "${extensionId}" should be visible on chrome://extensions`,
+      );
+    });
+  });
+
+  after(() => {
+    if (tmpDir) {
+      fs.rmSync(tmpDir, {recursive: true, force: true});
+    }
+  });
+});
diff --git a/tests/tools/extensions.test.ts b/tests/tools/extensions.test.ts
new file mode 100644
index 000000000..dfd48dc95
--- /dev/null
+++ b/tests/tools/extensions.test.ts
@@ -0,0 +1,69 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import assert from 'node:assert';
+import {describe, it} from 'node:test';
+
+import {installExtension} from '../../src/tools/extensions.js';
+import {withMcpContext} from '../utils.js';
+
+const EXTENSION_PATH = '/usr/local/google/home/nharshunova/test/extensions';
+const EXTENSION_ID = 'emhhlofcjnaambdnpppkpbcimdeaccnn';
+
+describe('extension', () => {
+  it('installs an extension and verifies it is listed in chrome://extensions', async () => {
+    await withMcpContext(async (response, context) => {
+      // 1. Install the extension
+      await installExtension.handler(
+        {params: {path: EXTENSION_PATH}},
+        response,
+        context,
+      );
+
+      // 2. Verify response
+      assert.ok(
+        response.responseLines[0]?.includes(EXTENSION_ID),
+        `Response should include extension ID ${EXTENSION_ID}`,
+      );
+
+      // 3. Verify extension is accessible by navigating to its popup
+      const page = context.getSelectedPage();
+      await page.goto(`chrome-extension://${EXTENSION_ID}/popup.html`);
+      const popupContent = await page.content();
+      assert.ok(
+        popupContent.includes('Popup Action'),
+        'Extension popup should be accessible',
+      );
+
+      // 4. Verify extension presence in chrome://extensions UI
+      // 4. Verify extension presence in chrome://extensions UI
+      await page.goto('chrome://extensions');
+
+      // Wait for usage to ensure page is loaded
+      await new Promise(r => setTimeout(r, 2000));
+
+      const EXTENSION_NAME = 'Simple Popup Action';
+      const found = await page.evaluate(extName => {
+        function deepSearch(root: Element | ShadowRoot): boolean {
+          if (root.textContent?.includes(extName)) return true;
+          if ('shadowRoot' in root && root.shadowRoot) {
+            if (deepSearch(root.shadowRoot)) return true;
+          }
+          for (const child of Array.from(root.children)) {
+            if (deepSearch(child)) return true;
+          }
+          return false;
+        }
+        return deepSearch(document.body);
+      }, EXTENSION_NAME);
+
+      assert.ok(
+        found,
+        `Extension "${EXTENSION_NAME}" should be visible on chrome://extensions`,
+      );
+    });
+  });
+});
diff --git a/tests/utils.ts b/tests/utils.ts
index f571ee721..d95384bcf 100644
--- a/tests/utils.ts
+++ b/tests/utils.ts
@@ -56,6 +56,7 @@ export async function withBrowser(
     pipe: true,
     handleDevToolsAsPage: true,
     args: ['--screen-info={3840x2160}'],
+    enableExtensions: true,
   };
   const key = JSON.stringify(launchOptions);
 

From 2d7a8dcfcfcb4511839544f9fc330db935b46755 Mon Sep 17 00:00:00 2001
From: Natallia Harshunova <nharshunova@chromium.org>
Date: Thu, 15 Jan 2026 13:23:31 +0000
Subject: [PATCH 3/9] Fix extension tests

---
 tests/tools/extension.test.ts  | 68 ----------------------------
 tests/tools/extensions.test.ts | 81 +++++++++++++++++-----------------
 2 files changed, 40 insertions(+), 109 deletions(-)
 delete mode 100644 tests/tools/extension.test.ts

diff --git a/tests/tools/extension.test.ts b/tests/tools/extension.test.ts
deleted file mode 100644
index 4ccd508c4..000000000
--- a/tests/tools/extension.test.ts
+++ /dev/null
@@ -1,68 +0,0 @@
-/**
- * @license
- * Copyright 2025 Google LLC
- * SPDX-License-Identifier: Apache-2.0
- */
-
-import assert from 'node:assert';
-import fs from 'node:fs';
-import os from 'node:os';
-import path from 'node:path';
-import {describe, it, after} from 'node:test';
-
-import {installExtension} from '../../src/tools/extensions.js';
-import {withMcpContext} from '../utils.js';
-
-describe('extension', () => {
-  let tmpDir: string;
-
-  it('installs an extension and verifies it is listed in chrome://extensions', async () => {
-    tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'extension-test-'));
-    fs.writeFileSync(
-      path.join(tmpDir, 'manifest.json'),
-      JSON.stringify({
-        manifest_version: 3,
-        name: 'Test Extension',
-        version: '1.0',
-        action: {
-          default_popup: 'popup.html',
-        },
-      }),
-    );
-    fs.writeFileSync(
-      path.join(tmpDir, 'popup.html'),
-      '<!DOCTYPE html><html><body><h1>Test Popup</h1></body></html>',
-    );
-
-    await withMcpContext(async (response, context) => {
-      await installExtension.handler(
-        {params: {path: tmpDir}},
-        response,
-        context,
-      );
-
-      const responseLine = response.responseLines[0];
-      assert.ok(responseLine, 'Response should not be empty');
-      const match = responseLine.match(/Extension installed\. Id: (.+)/);
-      const extensionId = match ? match[1] : null;
-      assert.ok(extensionId, 'Response should contain a valid key');
-
-      const page = context.getSelectedPage();
-      await page.goto('chrome://extensions');
-
-      const element = await page.waitForSelector(
-        `extensions-manager >>> extensions-item[id="${extensionId}"]`,
-      );
-      assert.ok(
-        element,
-        `Extension with ID "${extensionId}" should be visible on chrome://extensions`,
-      );
-    });
-  });
-
-  after(() => {
-    if (tmpDir) {
-      fs.rmSync(tmpDir, {recursive: true, force: true});
-    }
-  });
-});
diff --git a/tests/tools/extensions.test.ts b/tests/tools/extensions.test.ts
index dfd48dc95..dc4a37297 100644
--- a/tests/tools/extensions.test.ts
+++ b/tests/tools/extensions.test.ts
@@ -5,65 +5,64 @@
  */
 
 import assert from 'node:assert';
-import {describe, it} from 'node:test';
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+import { describe, it, after } from 'node:test';
 
 import {installExtension} from '../../src/tools/extensions.js';
 import {withMcpContext} from '../utils.js';
 
-const EXTENSION_PATH = '/usr/local/google/home/nharshunova/test/extensions';
-const EXTENSION_ID = 'emhhlofcjnaambdnpppkpbcimdeaccnn';
-
 describe('extension', () => {
+  let tmpDir: string;
+
   it('installs an extension and verifies it is listed in chrome://extensions', async () => {
+    tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'extension-test-'));
+    fs.writeFileSync(
+      path.join(tmpDir, 'manifest.json'),
+      JSON.stringify({
+        manifest_version: 3,
+        name: 'Test Extension',
+        version: '1.0',
+        action: {
+          default_popup: 'popup.html',
+        },
+      }),
+    );
+    fs.writeFileSync(
+      path.join(tmpDir, 'popup.html'),
+      '<!DOCTYPE html><html><body><h1>Test Popup</h1></body></html>',
+    );
+
     await withMcpContext(async (response, context) => {
-      // 1. Install the extension
       await installExtension.handler(
-        {params: {path: EXTENSION_PATH}},
+        { params: { path: tmpDir } },
         response,
         context,
       );
 
-      // 2. Verify response
-      assert.ok(
-        response.responseLines[0]?.includes(EXTENSION_ID),
-        `Response should include extension ID ${EXTENSION_ID}`,
-      );
+      const responseLine = response.responseLines[0];
+      assert.ok(responseLine, 'Response should not be empty');
+      const match = responseLine.match(/Extension installed\. Id: (.+)/);
+      const extensionId = match ? match[1] : null;
+      assert.ok(extensionId, 'Response should contain a valid key');
 
-      // 3. Verify extension is accessible by navigating to its popup
       const page = context.getSelectedPage();
-      await page.goto(`chrome-extension://${EXTENSION_ID}/popup.html`);
-      const popupContent = await page.content();
-      assert.ok(
-        popupContent.includes('Popup Action'),
-        'Extension popup should be accessible',
-      );
-
-      // 4. Verify extension presence in chrome://extensions UI
-      // 4. Verify extension presence in chrome://extensions UI
       await page.goto('chrome://extensions');
 
-      // Wait for usage to ensure page is loaded
-      await new Promise(r => setTimeout(r, 2000));
-
-      const EXTENSION_NAME = 'Simple Popup Action';
-      const found = await page.evaluate(extName => {
-        function deepSearch(root: Element | ShadowRoot): boolean {
-          if (root.textContent?.includes(extName)) return true;
-          if ('shadowRoot' in root && root.shadowRoot) {
-            if (deepSearch(root.shadowRoot)) return true;
-          }
-          for (const child of Array.from(root.children)) {
-            if (deepSearch(child)) return true;
-          }
-          return false;
-        }
-        return deepSearch(document.body);
-      }, EXTENSION_NAME);
-
+      const element = await page.waitForSelector(
+        `extensions-manager >>> extensions-item[id="${extensionId}"]`,
+      );
       assert.ok(
-        found,
-        `Extension "${EXTENSION_NAME}" should be visible on chrome://extensions`,
+        element,
+        `Extension with ID "${extensionId}" should be visible on chrome://extensions`,
       );
     });
   });
+
+  after(() => {
+    if (tmpDir) {
+      fs.rmSync(tmpDir, { recursive: true, force: true });
+    }
+  });
 });

From 181c46657974652d46eb7ad71849ed086078071e Mon Sep 17 00:00:00 2001
From: Natallia Harshunova <nharshunova@chromium.org>
Date: Thu, 15 Jan 2026 13:38:04 +0000
Subject: [PATCH 4/9] Update formatting

---
 tests/tools/extensions.test.ts | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tests/tools/extensions.test.ts b/tests/tools/extensions.test.ts
index dc4a37297..4ccd508c4 100644
--- a/tests/tools/extensions.test.ts
+++ b/tests/tools/extensions.test.ts
@@ -8,7 +8,7 @@ import assert from 'node:assert';
 import fs from 'node:fs';
 import os from 'node:os';
 import path from 'node:path';
-import { describe, it, after } from 'node:test';
+import {describe, it, after} from 'node:test';
 
 import {installExtension} from '../../src/tools/extensions.js';
 import {withMcpContext} from '../utils.js';
@@ -36,7 +36,7 @@ describe('extension', () => {
 
     await withMcpContext(async (response, context) => {
       await installExtension.handler(
-        { params: { path: tmpDir } },
+        {params: {path: tmpDir}},
         response,
         context,
       );
@@ -62,7 +62,7 @@ describe('extension', () => {
 
   after(() => {
     if (tmpDir) {
-      fs.rmSync(tmpDir, { recursive: true, force: true });
+      fs.rmSync(tmpDir, {recursive: true, force: true});
     }
   });
 });

From 4a2611deb536d76c9c7e862fd687bdf90c5c570c Mon Sep 17 00:00:00 2001
From: Natallia Harshunova <nharshunova@chromium.org>
Date: Thu, 15 Jan 2026 15:33:09 +0000
Subject: [PATCH 5/9] Hide extensions from docs

---
 README.md                |  2 --
 docs/tool-reference.md   | 18 ++----------------
 scripts/generate-docs.ts |  6 ++++++
 3 files changed, 8 insertions(+), 18 deletions(-)

diff --git a/README.md b/README.md
index 8b1681af9..1f663eb60 100644
--- a/README.md
+++ b/README.md
@@ -360,8 +360,6 @@ If you run into any issues, checkout our [troubleshooting guide](./docs/troubles
   - [`list_console_messages`](docs/tool-reference.md#list_console_messages)
   - [`take_screenshot`](docs/tool-reference.md#take_screenshot)
   - [`take_snapshot`](docs/tool-reference.md#take_snapshot)
-- **Extensions** (1 tools)
-  - [`install_extension`](docs/tool-reference.md#install_extension)
 
 <!-- END AUTO GENERATED TOOLS -->
 
diff --git a/docs/tool-reference.md b/docs/tool-reference.md
index 60895c56b..fd6b84a5b 100644
--- a/docs/tool-reference.md
+++ b/docs/tool-reference.md
@@ -34,8 +34,6 @@
   - [`list_console_messages`](#list_console_messages)
   - [`take_screenshot`](#take_screenshot)
   - [`take_snapshot`](#take_snapshot)
-- **[Extensions](#extensions)** (1 tools)
-  - [`install_extension`](#install_extension)
 
 ## Input automation
 
@@ -285,12 +283,12 @@ so returned values have to JSON-serializable.
 **Parameters:**
 
 - **function** (string) **(required)**: A JavaScript function declaration to be executed by the tool in the currently selected page.
-  Example without arguments: `() => {
+Example without arguments: `() => {
   return document.title
 }` or `async () => {
   return await fetch("example.com")
 }`.
-  Example with arguments: `(el) => {
+Example with arguments: `(el) => {
   return el.innerText;
 }`
 
@@ -347,15 +345,3 @@ in the DevTools Elements panel (if any).
 - **verbose** (boolean) _(optional)_: Whether to include all possible information available in the full a11y tree. Default is false.
 
 ---
-
-## Extensions
-
-### `install_extension`
-
-**Description:** Installs a Chrome extension from the given path.
-
-**Parameters:**
-
-- **path** (string) **(required)**: Absolute path to the unpacked extension folder.
-
----
diff --git a/scripts/generate-docs.ts b/scripts/generate-docs.ts
index 3294fd4ab..f98bacc94 100644
--- a/scripts/generate-docs.ts
+++ b/scripts/generate-docs.ts
@@ -281,6 +281,12 @@ async function generateToolDocumentation(): Promise<void> {
         if (!tool.annotations.conditions) {
           return true;
         }
+
+        // Filter out extension tools
+        if (tool.name === 'install_extension') {
+          return false;
+        }
+        
         // Only include unconditional tools.
         return tool.annotations.conditions.length === 0;
       })

From 25f85bb24a760550b554dffed8f5655347f6f0aa Mon Sep 17 00:00:00 2001
From: Natallia Harshunova <nharshunova@chromium.org>
Date: Thu, 15 Jan 2026 16:13:23 +0000
Subject: [PATCH 6/9] Fix pr comments

---
 src/tools/extensions.ts                      | 14 +++-----
 tests/tools/extensions.test.ts               | 37 ++++----------------
 tests/tools/fixtures/extension/manifest.json |  8 +++++
 tests/tools/fixtures/extension/popup.html    |  1 +
 4 files changed, 19 insertions(+), 41 deletions(-)
 create mode 100644 tests/tools/fixtures/extension/manifest.json
 create mode 100644 tests/tools/fixtures/extension/popup.html

diff --git a/src/tools/extensions.ts b/src/tools/extensions.ts
index 25537bd2a..c16689b62 100644
--- a/src/tools/extensions.ts
+++ b/src/tools/extensions.ts
@@ -1,10 +1,9 @@
 /**
  * @license
- * Copyright 2025 Google LLC
+ * Copyright 2026 Google LLC
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import {logger} from '../logger.js';
 import {zod} from '../third_party/index.js';
 
 import {ToolCategory} from './categories.js';
@@ -23,13 +22,8 @@ export const installExtension = defineTool({
       .describe('Absolute path to the unpacked extension folder.'),
   },
   handler: async (request, response, context) => {
-    const {path} = request.params;
-    try {
-      const id = await context.installExtension(path);
-      response.appendResponseLine(`Extension installed. Id: ${id}`);
-    } catch (error) {
-      logger('Extension installation error: ', error);
-      throw error;
-    }
+    const { path } = request.params;
+    const id = await context.installExtension(path);
+    response.appendResponseLine(`Extension installed. Id: ${id}`);
   },
 });
diff --git a/tests/tools/extensions.test.ts b/tests/tools/extensions.test.ts
index 4ccd508c4..fd9a1a225 100644
--- a/tests/tools/extensions.test.ts
+++ b/tests/tools/extensions.test.ts
@@ -5,38 +5,19 @@
  */
 
 import assert from 'node:assert';
-import fs from 'node:fs';
-import os from 'node:os';
 import path from 'node:path';
-import {describe, it, after} from 'node:test';
+import { describe, it } from 'node:test';
 
-import {installExtension} from '../../src/tools/extensions.js';
-import {withMcpContext} from '../utils.js';
+import { installExtension } from '../../src/tools/extensions.js';
+import { withMcpContext } from '../utils.js';
 
-describe('extension', () => {
-  let tmpDir: string;
+const EXTENSION_PATH = path.join(import.meta.dirname, '../../../tests/tools/fixtures/extension');
 
+describe('extension', () => {
   it('installs an extension and verifies it is listed in chrome://extensions', async () => {
-    tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'extension-test-'));
-    fs.writeFileSync(
-      path.join(tmpDir, 'manifest.json'),
-      JSON.stringify({
-        manifest_version: 3,
-        name: 'Test Extension',
-        version: '1.0',
-        action: {
-          default_popup: 'popup.html',
-        },
-      }),
-    );
-    fs.writeFileSync(
-      path.join(tmpDir, 'popup.html'),
-      '<!DOCTYPE html><html><body><h1>Test Popup</h1></body></html>',
-    );
-
     await withMcpContext(async (response, context) => {
       await installExtension.handler(
-        {params: {path: tmpDir}},
+        { params: { path: EXTENSION_PATH } },
         response,
         context,
       );
@@ -59,10 +40,4 @@ describe('extension', () => {
       );
     });
   });
-
-  after(() => {
-    if (tmpDir) {
-      fs.rmSync(tmpDir, {recursive: true, force: true});
-    }
-  });
 });
diff --git a/tests/tools/fixtures/extension/manifest.json b/tests/tools/fixtures/extension/manifest.json
new file mode 100644
index 000000000..fc0304f0b
--- /dev/null
+++ b/tests/tools/fixtures/extension/manifest.json
@@ -0,0 +1,8 @@
+{
+  "manifest_version": 3,
+  "name": "Test Extension",
+  "version": "1.0",
+  "action": {
+    "default_popup": "popup.html"
+  }
+}
diff --git a/tests/tools/fixtures/extension/popup.html b/tests/tools/fixtures/extension/popup.html
new file mode 100644
index 000000000..27f262c04
--- /dev/null
+++ b/tests/tools/fixtures/extension/popup.html
@@ -0,0 +1 @@
+<!DOCTYPE html><html><body><h1>Test Popup</h1></body></html>

From be49b6ba4b0cf5caceaa158cf7841ed305597011 Mon Sep 17 00:00:00 2001
From: Natallia Harshunova <nharshunova@chromium.org>
Date: Thu, 15 Jan 2026 16:29:33 +0000
Subject: [PATCH 7/9] Move extension test to fixtures

---
 docs/tool-reference.md                    |  4 ++--
 scripts/generate-docs.ts                  | 10 +++++-----
 src/tools/extensions.ts                   |  2 +-
 tests/tools/extensions.test.ts            | 13 ++++++++-----
 tests/tools/fixtures/extension/popup.html |  7 ++++++-
 5 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/docs/tool-reference.md b/docs/tool-reference.md
index fd6b84a5b..ac8ab1f53 100644
--- a/docs/tool-reference.md
+++ b/docs/tool-reference.md
@@ -283,12 +283,12 @@ so returned values have to JSON-serializable.
 **Parameters:**
 
 - **function** (string) **(required)**: A JavaScript function declaration to be executed by the tool in the currently selected page.
-Example without arguments: `() => {
+  Example without arguments: `() => {
   return document.title
 }` or `async () => {
   return await fetch("example.com")
 }`.
-Example with arguments: `(el) => {
+  Example with arguments: `(el) => {
   return el.innerText;
 }`
 
diff --git a/scripts/generate-docs.ts b/scripts/generate-docs.ts
index f98bacc94..4cfd316cc 100644
--- a/scripts/generate-docs.ts
+++ b/scripts/generate-docs.ts
@@ -278,15 +278,15 @@ async function generateToolDocumentation(): Promise<void> {
     // Convert ToolDefinitions to ToolWithAnnotations
     const toolsWithAnnotations: ToolWithAnnotations[] = tools
       .filter(tool => {
-        if (!tool.annotations.conditions) {
-          return true;
-        }
-
         // Filter out extension tools
         if (tool.name === 'install_extension') {
           return false;
         }
-        
+
+        if (!tool.annotations.conditions) {
+          return true;
+        }
+
         // Only include unconditional tools.
         return tool.annotations.conditions.length === 0;
       })
diff --git a/src/tools/extensions.ts b/src/tools/extensions.ts
index c16689b62..245c25b7a 100644
--- a/src/tools/extensions.ts
+++ b/src/tools/extensions.ts
@@ -22,7 +22,7 @@ export const installExtension = defineTool({
       .describe('Absolute path to the unpacked extension folder.'),
   },
   handler: async (request, response, context) => {
-    const { path } = request.params;
+    const {path} = request.params;
     const id = await context.installExtension(path);
     response.appendResponseLine(`Extension installed. Id: ${id}`);
   },
diff --git a/tests/tools/extensions.test.ts b/tests/tools/extensions.test.ts
index fd9a1a225..cd754c29a 100644
--- a/tests/tools/extensions.test.ts
+++ b/tests/tools/extensions.test.ts
@@ -6,18 +6,21 @@
 
 import assert from 'node:assert';
 import path from 'node:path';
-import { describe, it } from 'node:test';
+import {describe, it} from 'node:test';
 
-import { installExtension } from '../../src/tools/extensions.js';
-import { withMcpContext } from '../utils.js';
+import {installExtension} from '../../src/tools/extensions.js';
+import {withMcpContext} from '../utils.js';
 
-const EXTENSION_PATH = path.join(import.meta.dirname, '../../../tests/tools/fixtures/extension');
+const EXTENSION_PATH = path.join(
+  import.meta.dirname,
+  '../../../tests/tools/fixtures/extension',
+);
 
 describe('extension', () => {
   it('installs an extension and verifies it is listed in chrome://extensions', async () => {
     await withMcpContext(async (response, context) => {
       await installExtension.handler(
-        { params: { path: EXTENSION_PATH } },
+        {params: {path: EXTENSION_PATH}},
         response,
         context,
       );
diff --git a/tests/tools/fixtures/extension/popup.html b/tests/tools/fixtures/extension/popup.html
index 27f262c04..72cb44d64 100644
--- a/tests/tools/fixtures/extension/popup.html
+++ b/tests/tools/fixtures/extension/popup.html
@@ -1 +1,6 @@
-<!DOCTYPE html><html><body><h1>Test Popup</h1></body></html>
+<!doctype html>
+<html
+  ><body
+    ><h1>Test Popup</h1></body
+  ></html
+>

From f94c6aa8eaacea978d026cc206160ae0548b1bef Mon Sep 17 00:00:00 2001
From: Natallia Harshunova <nharshunova@chromium.org>
Date: Thu, 15 Jan 2026 16:38:03 +0000
Subject: [PATCH 8/9] Update license year

---
 tests/tools/extensions.test.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/tools/extensions.test.ts b/tests/tools/extensions.test.ts
index cd754c29a..f1ed6566f 100644
--- a/tests/tools/extensions.test.ts
+++ b/tests/tools/extensions.test.ts
@@ -1,6 +1,6 @@
 /**
  * @license
- * Copyright 2025 Google LLC
+ * Copyright 2026 Google LLC
  * SPDX-License-Identifier: Apache-2.0
  */
 

From 6b7f2a939362f59f0f7be328e25d6118916ce6d2 Mon Sep 17 00:00:00 2001
From: Natallia Harshunova <nharshunova@chromium.org>
Date: Fri, 16 Jan 2026 11:02:08 +0000
Subject: [PATCH 9/9] pr comments

---
 src/browser.ts                            |  3 ++-
 src/main.ts                               |  1 +
 tests/tools/fixtures/extension/popup.html | 10 +++++-----
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/browser.ts b/src/browser.ts
index 71e9376ca..64db15681 100644
--- a/src/browser.ts
+++ b/src/browser.ts
@@ -145,6 +145,7 @@ interface McpLaunchOptions {
   chromeArgs?: string[];
   ignoreDefaultChromeArgs?: string[];
   devtools: boolean;
+  enableExtensions?: boolean;
 }
 
 export async function launch(options: McpLaunchOptions): Promise<Browser> {
@@ -201,7 +202,7 @@ export async function launch(options: McpLaunchOptions): Promise<Browser> {
       ignoreDefaultArgs: ignoreDefaultArgs,
       acceptInsecureCerts: options.acceptInsecureCerts,
       handleDevToolsAsPage: true,
-      enableExtensions: true,
+      enableExtensions: options.enableExtensions,
     });
     if (options.logFile) {
       // FIXME: we are probably subscribing too late to catch startup logs. We
diff --git a/src/main.ts b/src/main.ts
index 665dd1cf7..0c0dc9735 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -91,6 +91,7 @@ async function getContext(): Promise<McpContext> {
           ignoreDefaultChromeArgs,
           acceptInsecureCerts: args.acceptInsecureCerts,
           devtools,
+          enableExtensions: args.categoryExtensions,
         });
 
   if (context?.browser !== browser) {
diff --git a/tests/tools/fixtures/extension/popup.html b/tests/tools/fixtures/extension/popup.html
index 72cb44d64..c5c00a395 100644
--- a/tests/tools/fixtures/extension/popup.html
+++ b/tests/tools/fixtures/extension/popup.html
@@ -1,6 +1,6 @@
 <!doctype html>
-<html
-  ><body
-    ><h1>Test Popup</h1></body
-  ></html
->
+<html>
+  <body>
+    <h1>Test Popup</h1>
+  </body>
+</html>