main.ts

/**
 * @license
 * Copyright 2025 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

import assert from 'node:assert';
import fs from 'node:fs';
import path from 'node:path';

import {McpServer} from '@modelcontextprotocol/sdk/server/mcp.js';
import {StdioServerTransport} from '@modelcontextprotocol/sdk/server/stdio.js';
import type {CallToolResult} from '@modelcontextprotocol/sdk/types.js';
import {SetLevelRequestSchema} from '@modelcontextprotocol/sdk/types.js';

import type {Channel} from './browser.js';
import {resolveBrowser} from './browser.js';
import {parseArguments} from './cli.js';
import {logger, saveLogsToFile} from './logger.js';
import {McpContext} from './McpContext.js';
import {McpResponse} from './McpResponse.js';
import {Mutex} from './Mutex.js';
import * as consoleTools from './tools/console.js';
import * as emulationTools from './tools/emulation.js';
import * as inputTools from './tools/input.js';
import * as networkTools from './tools/network.js';
import * as pagesTools from './tools/pages.js';
import * as performanceTools from './tools/performance.js';
import * as screenshotTools from './tools/screenshot.js';
import * as scriptTools from './tools/script.js';
import * as snapshotTools from './tools/snapshot.js';
import type {ToolDefinition} from './tools/ToolDefinition.js';

function readPackageJson(): {version?: string} {
  const currentDir = import.meta.dirname;
  const packageJsonPath = path.join(currentDir, '..', '..', 'package.json');
  if (!fs.existsSync(packageJsonPath)) {
    return {};
  }
  try {
    const json = JSON.parse(fs.readFileSync(packageJsonPath, 'utf-8'));
    assert.strict(json['name'], 'chrome-devtools-mcp');
    return json;
  } catch {
    return {};
  }
}

const version = readPackageJson().version ?? 'unknown';

export const args = parseArguments(version);

const logFile = args.logFile ? saveLogsToFile(args.logFile) : undefined;

logger(`Starting Chrome DevTools MCP Server v${version}`);
const server = new McpServer(
  {
    name: 'chrome_devtools',
    title: 'Chrome DevTools MCP server',
    version,
  },
  {capabilities: {logging: {}}},
);
server.server.setRequestHandler(SetLevelRequestSchema, () => {
  return {};
});

let context: McpContext;
async function getContext(): Promise<McpContext> {
  const browser = await resolveBrowser({
    browserUrl: args.browserUrl,
    headless: args.headless,
    executablePath: args.executablePath,
    customDevTools: args.customDevtools,
    channel: args.channel as Channel,
    isolated: args.isolated,
    logFile,
  });
  if (context?.browser !== browser) {
    context = await McpContext.from(browser, logger);
  }
  return context;
}

const logDisclaimers = () => {
  console.error(
    `chrome-devtools-mcp exposes content of the browser instance to the MCP clients allowing them to inspect,
debug, and modify any data in the browser or DevTools.
Avoid sharing sensitive or personal information that you do want to share with MCP clients.`,
  );
};

const toolMutex = new Mutex();

function registerTool(tool: ToolDefinition): void {
  server.registerTool(
    tool.name,
    {
      description: tool.description,
      inputSchema: tool.schema,
      annotations: tool.annotations,
    },
    async (params): Promise<CallToolResult> => {
      const guard = await toolMutex.acquire();
      try {
        logger(`${tool.name} request: ${JSON.stringify(params, null, '  ')}`);
        const context = await getContext();
        const response = new McpResponse();
        await tool.handler(
          {
            params,
          },
          response,
          context,
        );
        try {
          const content = await response.handle(tool.name, context);
          return {
            content,
          };
        } catch (error) {
          const errorText =
            error instanceof Error ? error.message : String(error);

          return {
            content: [
              {
                type: 'text',
                text: errorText,
              },
            ],
            isError: true,
          };
        }
      } finally {
        guard.dispose();
      }
    },
  );
}

const tools = [
  ...Object.values(consoleTools),
  ...Object.values(emulationTools),
  ...Object.values(inputTools),
  ...Object.values(networkTools),
  ...Object.values(pagesTools),
  ...Object.values(performanceTools),
  ...Object.values(screenshotTools),
  ...Object.values(scriptTools),
  ...Object.values(snapshotTools),
];
for (const tool of tools) {
  registerTool(tool as unknown as ToolDefinition);
}

const transport = new StdioServerTransport();
await server.connect(transport);
logger('Chrome DevTools MCP Server connected');
logDisclaimers();