Playwright MCP Setup

Playwright MCP Setup — Full Guide

Complete setup guide for Playwright MCP with the Chrome extension in Claude Code. This enables Claude to control your existing Chrome browser (with your logged-in sessions) instead of launching a new headless browser.

Why Extension Mode?

By default, Playwright MCP launches a fresh Chromium browser with no sessions. With extension mode, it connects to your real Chrome — keeping all logins, cookies, extensions, and profiles. This is essential for automating social media, authenticated dashboards, and any site where you're already logged in.

Prerequisites

• Google Chrome installed at /Applications/Google Chrome.app
• Claude Code installed and working

Step 1: Install the Playwright MCP Bridge Extension

1. Open Chrome and navigate to the Chrome Web Store
2. Search for "Playwright MCP Bridge" or go directly to the extension page
3. Click "Add to Chrome" to install
4. The extension ID is: mmlmfjhmonkocbjadbfplnigmagldckm

Verify installation: Check Chrome shows the extension icon in the toolbar, or navigate to chrome://extensions and confirm "Playwright MCP Bridge" is listed and enabled.

Step 2: Get the Extension Token

1. Click the Playwright MCP Bridge extension icon in Chrome's toolbar, or navigate to:

   chrome-extension://mmlmfjhmonkocbjadbfplnigmagldckm/status.html
   

2. The page shows your token in the format:

   PLAYWRIGHT_MCP_EXTENSION_TOKEN=<your-token-here>
   

3. Copy the token value (the part after =)

How the token works: On first load, the extension generates a random 32-byte base64url token and stores it in localStorage. This token authenticates the MCP server connection to prevent unauthorized access to your browser.

Step 3: Configure Claude Code

Option A: Official Playwright Plugin (Recommended)

If you installed the official Playwright plugin via /install-plugin playwright, Claude Code automatically detects the extension and runs with --extension flag. The plugin config lives at:

~/.claude/plugins/marketplaces/claude-plugins-official/external_plugins/playwright/.mcp.json

You may need to set the token as an environment variable. Add to your shell profile (~/.zshrc):

export PLAYWRIGHT_MCP_EXTENSION_TOKEN="your-token-here"

Option B: Manual MCP Server Configuration

Add to your ~/.claude/settings.json under mcpServers:

{
  "mcpServers": {
    "playwright-extension": {
      "command": "npx",
      "args": ["@playwright/mcp@latest", "--extension"],
      "env": {
        "PLAYWRIGHT_MCP_EXTENSION_TOKEN": "your-token-here"
      }
    }
  }
}

Or in a project-level .mcp.json:

{
  "playwright-extension": {
    "command": "npx",
    "args": ["@playwright/mcp@latest", "--extension"],
    "env": {
      "PLAYWRIGHT_MCP_EXTENSION_TOKEN": "your-token-here"
    }
  }
}

Step 4: Verify Connection

1. Restart Claude Code (or run /mcp to reconnect MCP servers)
2. Chrome should show an info bar: "Playwright MCP Bridge started debugging this browser" with a Cancel button
3. Test with a simple command like browser_snapshot — it should return the current page's accessibility tree

If the info bar doesn't appear, check:

• The extension is enabled in chrome://extensions
• The token matches between your config and the extension's status page
• Chrome is running

Step 5: Enable File Upload Support (Important!)

By default, browser_file_upload and fileChooser.setFiles() fail with "Not allowed" due to Chrome's CDP security restriction on extensions. To fix this:

1. Navigate to chrome://extensions in Chrome (use macOS-use if Playwright can't access chrome:// URLs)
2. Find "Playwright MCP Bridge" and click "Details"
3. Scroll down and enable "Allow access to file URLs" toggle
4. Restart Chrome for the setting to take effect

After this, file uploads work using browser_run_code:

async (page) => {
  const [fileChooser] = await Promise.all([
    page.waitForEvent('filechooser', { timeout: 5000 }),
    page.getByRole('button', { name: 'Upload' }).click()
  ]);
  await fileChooser.setFiles('/absolute/path/to/file.png');
  return 'File uploaded';
}

Note: The file path must be within Playwright MCP's allowed roots (typically the project directory). Copy files there first if needed.

Automating the File URL Toggle

This setting cannot be enabled purely programmatically — Chrome protects extension preferences with HMAC-SHA256 validation in Secure Preferences. The only reliable approaches are:

1. Automate the UI with macOS-use (recommended for agent setup):

   # Use macOS-use to navigate chrome://extensions (Playwright can't access chrome:// URLs)
   1. open_application_and_traverse Chrome
   2. Click address bar, type "chrome://extensions", press Return
   3. Find "Playwright MCP Bridge" heading, click its "Details" button
   4. Find "Allow access to file URLs" toggle, click it
   5. Restart Chrome
   

2. Chrome enterprise policy (for fleet deployment): Deploy ExtensionSettings policy via MDM to pre-configure the setting.

Where the setting is stored: ~/Library/Application Support/Google/Chrome/<Profile>/Secure Preferences under extensions.settings.<extension_id>.newAllowFileAccess (boolean). The file is HMAC-protected — direct edits are detected and reverted by Chrome.

Architecture

Claude Code  -->  Playwright MCP Server (--extension flag)
                       |
                       | WebSocket (localhost only)
                       v
              Playwright MCP Bridge Extension (Chrome)
                       |
                       | Chrome DevTools Protocol (CDP)
                       v
                  Your Chrome Browser (tabs, pages)

• Playwright MCP Server: Node.js process (npx @playwright/mcp@latest --extension) that exposes MCP tools
• Playwright MCP Bridge Extension: Chrome extension that relays CDP commands to browser tabs
• Token: Shared secret ensuring only authorized MCP servers connect
• Security: WebSocket connections restricted to localhost (127.0.0.1 / [::1])

Troubleshooting

"Not allowed" on file upload

Enable "Allow access to file URLs" in extension details (see Step 5). Restart Chrome.

File chooser modal expires

Don't use separate browser_click + browser_file_upload calls — the modal expires between tool calls. Use browser_run_code to do click + setFiles atomically.

"File access denied: path is outside allowed roots"

Playwright MCP restricts file paths to the project directory. Copy the file into the project first:

cp ~/Downloads/photo.png ./photo.png

Can't navigate to chrome:// URLs

Playwright can't access chrome:// pages (blocked by CDP). Use macOS-use (click_and_traverse, type_and_traverse) to interact with Chrome settings pages.

Extension not detected / no debugging bar

• Verify extension is installed and enabled at chrome://extensions
• Check the token matches: compare PLAYWRIGHT_MCP_EXTENSION_TOKEN env var with the token shown at chrome-extension://mmlmfjhmonkocbjadbfplnigmagldckm/status.html
• Restart Claude Code (/mcp to reconnect)

Playwright locks / multi-agent conflicts

If multiple Claude agents share one browser, consider using lock mechanisms to prevent conflicts.

Desktop App Onboarding Pattern

If building a desktop app that needs to onboard users to Playwright MCP, here's a proven 4-phase flow:

1. Welcome — explain browser access capability
2. Connect — check Chrome installed, check extension installed (poll every 2s scanning Chrome profile directories for extension ID), open status.html, collect token
3. Verify — run a test Playwright connection to confirm everything works
4. Done — confirmation

Detection logic:

• Chrome installed: check for Chrome app at standard install path
• Extension installed: scan Chrome profile directories for Extensions/<extension_id>
• Token validation: 20+ chars, base64url format ([A-Za-z0-9_-]+)