feat: --minimal mode with maximum token savings

Author: OrKoN

README.md

@@ -525,6 +525,11 @@ The Chrome DevTools MCP server supports the following configuration option:
   - **Type:** boolean
   - **Default:** `true`
 
+- **`--minimal`, `-min`**
+  Minimal set of tools (only 3).
+  - **Type:** boolean
+  - **Default:** `false`
+
 <!-- END AUTO GENERATED OPTIONS -->
 
 Pass them via the `args` property in the JSON configuration. For example:

src/MinimalMcpResponse.ts

@@ -0,0 +1,32 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import type {
+  TextContent,
+  ImageContent,
+} from '@modelcontextprotocol/sdk/types.js';
+
+import type {McpContext} from './McpContext.js';
+import {McpResponse} from './McpResponse.js';
+
+export class MinimalMcpResponse extends McpResponse {
+  override async handle(
+    _toolName: string,
+    _context: McpContext,
+  ): Promise<{
+    content: Array<TextContent | ImageContent>;
+    structuredContent: object;
+  }> {
+    const text: TextContent = {
+      type: 'text',
+      text: this.responseLines.join('\n'),
+    };
+    return {
+      content: [text],
+      structuredContent: text,
+    };
+  }
+}

src/cli.ts

@@ -231,6 +231,11 @@ export const cliOptions = {
     hidden: true,
     describe: 'Include watchdog PID in Clearcut request headers (for testing).',
   },
+  minimal: {
+    type: 'boolean',
+    describe: 'Minimal set of tools (only 3).',
+    alias: 'min',
+  },
 } satisfies Record<string, YargsOptions>;
 
 export function parseArguments(version: string, argv = process.argv) {
@@ -307,6 +312,7 @@ export function parseArguments(version: string, argv = process.argv) {
         '$0 --no-performance-crux',
         'Disable CrUX (field data) integration in performance tools.',
       ],
+      ['$0 --minimal', 'Only 3 tools: navigation, JavaScript and screenshot'],
     ]);
 
   return yargsInstance

src/main.ts

@@ -15,6 +15,7 @@ import {loadIssueDescriptions} from './issue-descriptions.js';
 import {logger, saveLogsToFile} from './logger.js';
 import {McpContext} from './McpContext.js';
 import {McpResponse} from './McpResponse.js';
+import {MinimalMcpResponse} from './MinimalMcpResponse.js';
 import {Mutex} from './Mutex.js';
 import {ClearcutLogger} from './telemetry/ClearcutLogger.js';
 import {computeFlagUsage} from './telemetry/flagUtils.js';
@@ -26,6 +27,7 @@ import {
   SetLevelRequestSchema,
 } from './third_party/index.js';
 import {ToolCategory} from './tools/categories.js';
+import {tools as minimalTools} from './tools/minimal/tools.js';
 import type {ToolDefinition} from './tools/ToolDefinition.js';
 import {tools} from './tools/tools.js';
 
@@ -128,13 +130,13 @@ debug, and modify any data in the browser or DevTools.
 Avoid sharing sensitive or personal information that you do not want to share with MCP clients.`,
   );
 
-  if (args.performanceCrux) {
+  if (!args.minimal && args.performanceCrux) {
     console.error(
       `Performance tools may send trace URLs to the Google CrUX API to fetch real-user experience data. To disable, run with --no-performance-crux.`,
     );
   }
 
-  if (args.usageStatistics) {
+  if (!args.minimal && args.usageStatistics) {
     console.error(
       `
 Google collects usage statistics to improve Chrome DevTools MCP. To opt-out, run with --no-usage-statistics.
@@ -198,7 +200,9 @@ function registerTool(tool: ToolDefinition): void {
         const context = await getContext();
         logger(`${tool.name} context: resolved`);
         await context.detectOpenDevToolsWindows();
-        const response = new McpResponse();
+        const response = args.minimal
+          ? new MinimalMcpResponse()
+          : new McpResponse();
         await tool.handler(
           {
             params,
@@ -250,7 +254,7 @@ function registerTool(tool: ToolDefinition): void {
   );
 }
 
-for (const tool of tools) {
+for (const tool of args.minimal ? minimalTools : tools) {
   registerTool(tool);
 }
 

src/tools/minimal/tools.ts

@@ -0,0 +1,96 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import type {Dialog} from '../../third_party/index.js';
+import {zod} from '../../third_party/index.js';
+import {ToolCategory} from '../categories.js';
+import type {ToolDefinition} from '../ToolDefinition.js';
+import {defineTool} from '../ToolDefinition.js';
+
+export const screenshot = defineTool({
+  name: 'screenshot',
+  description: `Take page screenshot`,
+  annotations: {
+    category: ToolCategory.DEBUGGING,
+    // Not read-only due to filePath param.
+    readOnlyHint: false,
+  },
+  schema: {},
+  handler: async (request, response, context) => {
+    const page = context.getSelectedPage();
+    const screenshot = await page.screenshot({
+      type: 'png',
+      optimizeForSpeed: true, // Bonus: optimize encoding for speed
+    });
+    const {filename} = await context.saveTemporaryFile(screenshot, `image/png`);
+    response.appendResponseLine(filename);
+  },
+});
+
+export const navigatePage = defineTool({
+  name: 'navigate',
+  description: `Load URL in the browser`,
+  annotations: {
+    category: ToolCategory.NAVIGATION,
+    readOnlyHint: false,
+  },
+  schema: {
+    url: zod.string().describe('Page URL'),
+  },
+  handler: async (request, response, context) => {
+    const page = context.getSelectedPage();
+    const options = {
+      timeout: 30_000,
+    };
+
+    const dialogHandler = (dialog: Dialog) => {
+      if (dialog.type() === 'beforeunload') {
+        response.appendResponseLine(`Accepted a beforeunload dialog.`);
+        void dialog.accept();
+        // We are not going to report the dialog like regular dialogs.
+        context.clearDialog();
+      }
+    };
+
+    page.on('dialog', dialogHandler);
+
+    try {
+      await page.goto(request.params.url, options);
+    } finally {
+      page.off('dialog', dialogHandler);
+    }
+  },
+});
+
+export const evaluateScript = defineTool({
+  name: 'evaluate',
+  description: `Evaluate a JavaScript function`,
+  annotations: {
+    category: ToolCategory.DEBUGGING,
+    readOnlyHint: false,
+  },
+  schema: {
+    fn: zod
+      .string()
+      .describe(`A JavaScript function to be executed on the active page`),
+  },
+  handler: async (request, response, context) => {
+    const page = context.getSelectedPage();
+    const fn = await page.evaluateHandle(`(${request.params.fn})`);
+    const result = await page.evaluate(async fn => {
+      // @ts-expect-error no types.
+      return JSON.stringify(await fn());
+    }, fn);
+    response.appendResponseLine(result);
+    void fn.dispose();
+  },
+});
+
+export const tools = [
+  screenshot,
+  evaluateScript,
+  navigatePage,
+] as ToolDefinition[];

tests/index.test.ts

@@ -92,7 +92,7 @@ describe('e2e', () => {
       const files = fs.readdirSync('build/src/tools');
       const definedNames = [];
       for (const file of files) {
-        if (file === 'ToolDefinition.js') {
+        if (file === 'ToolDefinition.js' || file === 'minimal') {
           continue;
         }
         const fileTools = await import(`../src/tools/${file}`);