Ultimate Playwright

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Multi-agent Playwright MCP server with tab isolation via targetId. Allows multiple Claude instances (or other MCP clients) to share a single Chrome browser while maintaining isolated tab groups.

Why Ultimate Playwright?

The official @playwright/mcp gives you browser control for a single agent. But what if you have multiple agents sharing one browser?

Ultimate Playwright MCP solves this with tab group isolation:

• 🔀 Multi-agent tab groups — Each agent creates a groupId and only sees its own tabs
• 🍪 Shared cookies & sessions — All agents share the same BrowserContext (log in once, everyone's authenticated)
• 🎨 Visual Chrome tab groups — Companion extension organizes tabs into color-coded Chrome tab groups
• 💾 Persistent registry — Tab groups survive MCP server restarts (~/.ultimate-playwright-mcp/tab-groups.json)
• 🔌 Connect to existing Chrome — Uses CDP to attach to your running Chrome (keeps your profile, extensions, bookmarks)

Comparison

Feature	ultimate-playwright-mcp	@playwright/mcp	browser-use-mcp
Multi-agent tab isolation	✅ Tab groups with groupId	❌ Single session	❌ Single session
Shared cookies across agents	✅ Same BrowserContext	N/A	N/A
Connect to existing Chrome	✅ CDP	❌ Launches new browser	❌ Launches new browser
Visual tab groups in Chrome	✅ Extension	❌	❌
Persistent tab registry	✅ Survives restarts	❌	❌
Accessibility tree snapshots	✅ Element refs (e1, e2…)	✅	❌ Screenshot-based
Open source	✅ MIT	✅ Apache-2.0	✅ MIT

Features

• ✅ Tab Isolation - Each agent gets its own tabs via unique targetId
• ✅ Shared Cookies - All agents share the same BrowserContext (cookies, sessions, localStorage)
• ✅ Parallel Execution - Multiple agents can operate simultaneously without interference
• ✅ CDP Connection - Connects to existing Chrome via Chrome DevTools Protocol
• ✅ Native Page Checkpoints - Capture structured artifacts and generate reports per targetId
• ✅ Battle-Tested - Extracted from OpenClaw (MIT licensed)

Installation

npm install -g ultimate-playwright-mcp

Or run directly with npx:

npx ultimate-playwright-mcp --cdp-endpoint http://localhost:9222

Quick Start

1. Launch Chrome with Remote Debugging

# macOS
/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome \
  --remote-debugging-port=9222 \
  --user-data-dir=/tmp/chrome-debug

# Linux
google-chrome --remote-debugging-port=9222 --user-data-dir=/tmp/chrome-debug

# Windows
"C:\\Program Files\\Google\\Chrome\\Application\\chrome.exe" ^
  --remote-debugging-port=9222 ^
  --user-data-dir=C:\\temp\\chrome-debug

2. Configure Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "ultimate-playwright": {
      "command": "npx",
      "args": [
        "ultimate-playwright-mcp",
        "--cdp-endpoint",
        "http://localhost:9222"
      ]
    }
  }
}

3. Restart Claude Desktop

Claude will now have access to browser control tools with tab isolation.

Usage Example

User: Open two tabs and navigate them independently

Claude: I'll create two tabs with separate targetIds:

1. browser_tabs({ action: "new" })
   → **targetId: ABC123...**

2. browser_tabs({ action: "new" })
   → **targetId: XYZ789...**

3. browser_navigate({ targetId: "ABC123...", url: "https://github.com" })
4. browser_navigate({ targetId: "XYZ789...", url: "https://google.com" })

Both tabs are now navigated independently!

Available Tools

Tool	Description	Key Parameters
browser_tab_group	Create/list/delete tab groups for isolation	action, name, color, groupId
browser_tabs	List, create, close, or select tabs	action, groupId, targetId, index
browser_navigate	Navigate to a URL	url, targetId
browser_snapshot	Capture accessibility tree with refs	targetId
browser_click	Click an element	ref, targetId
browser_type	Type text into an element	ref, text, targetId
browser_hover	Hover over an element	ref, targetId
browser_press_key	Press a keyboard key	key, targetId
browser_fill_form	Fill multiple form fields	fields, targetId
browser_wait_for	Wait for conditions	text, selector, url, loadState, targetId
browser_checkpoint	Capture a structured checkpoint for a tab	name, targetId, collectors
browser_checkpoint_report	Generate reports from stored checkpoints	format, resultsDir

Checkpoints

Use browser_checkpoint when you want a persisted capture of the current page for later review or report generation.

• Checkpoints are scoped to the resolved targetId, so they work with this server's tab isolation model.
• Artifacts and manifests are written under ~/.ultimate-playwright-mcp/checkpoints by default.
• Generated reports are written under ~/.ultimate-playwright-mcp/checkpoints/report.

Example:

1. browser_checkpoint({ targetId: "ABC123", name: "after-login" })
2. browser_checkpoint_report({ format: "html" })

Tab Groups (Multi-User Isolation)

When multiple users or agents share one browser instance, tab groups keep everyone's tabs isolated. Each session creates its own group, and all tab operations are scoped to that group.

User: Research product pricing

Claude: I'll create a tab group first, then open tabs within it.

1. browser_tab_group({ action: "create", name: "pricing-research", color: "blue" })
   → **groupId: g_a1b2c3d4e5f6**

2. browser_tabs({ action: "new", groupId: "g_a1b2c3d4e5f6", url: "https://example.com/pricing" })
   → **targetId: ABC123...**

3. browser_tabs({ action: "list", groupId: "g_a1b2c3d4e5f6" })
   → Only shows tabs in this group (not other users' tabs)

Meanwhile, another user on the same server:

1. browser_tab_group({ action: "create", name: "docs-review", color: "green" })
   → **groupId: g_x9y8z7w6v5u4**

2. browser_tabs({ action: "new", groupId: "g_x9y8z7w6v5u4", url: "https://docs.example.com" })
   → **targetId: XYZ789...**

Both users share the same cookies/sessions but only see their own tabs!

Tab Group Lifecycle

1. Create a group at the start of your session
2. Open tabs within the group using groupId
3. Work with tabs using targetId as before
4. Delete the group when done (optionally closes all tabs)

Group state is persisted to ~/.ultimate-playwright-mcp/tab-groups.json so it survives MCP server restarts.

Architecture

┌─────────────────────────────────────────────┐
│        Single Chrome Process                │
│    (--remote-debugging-port=9222)           │
│  ┌─────────────────────────────────────┐   │
│  │     Single BrowserContext            │   │
│  │  (shared cookies, storage)           │   │
│  │                                      │   │
│  │  Group: alice (blue)                 │   │
│  │  ┌─────┐ ┌─────┐                    │   │
│  │  │ Tab │ │ Tab │                    │   │
│  │  │  A  │ │  B  │                    │   │
│  │  └─────┘ └─────┘                    │   │
│  │                                      │   │
│  │  Group: bob (green)                  │   │
│  │  ┌─────┐ ┌─────┐ ┌─────┐            │   │
│  │  │ Tab │ │ Tab │ │ Tab │            │   │
│  │  │  C  │ │  D  │ │  E  │            │   │
│  │  └─────┘ └─────┘ └─────┘            │   │
│  └─────────────────────────────────────┘   │
└─────────────────────────────────────────────┘
                   ↑
           CDP Connection
                   ↓
┌─────────────────────────────────────────────┐
│    ultimate-playwright-mcp (MCP Server)     │
│    - Tab routing via targetId               │
│    - Tab groups via groupId                 │
│    - Shared ownership registry (JSON file)  │
│    - Stdio transport                        │
└─────────────────────────────────────────────┘
         ↓           ↓           ↓
   ┌─────────┐ ┌─────────┐ ┌─────────┐
   │ Alice   │ │  Bob    │ │ Charlie │
   │ (Claude)│ │ (Claude)│ │ (Cursor)│
   └─────────┘ └─────────┘ └─────────┘

MCP Configuration

Cursor / Windsurf / Generic MCP Client

{
  "mcpServers": {
    "ultimate-playwright": {
      "command": "npx",
      "args": ["ultimate-playwright-mcp", "--cdp-endpoint", "http://localhost:9222"]
    }
  }
}

With Environment Variable

{
  "mcpServers": {
    "ultimate-playwright": {
      "command": "npx",
      "args": ["ultimate-playwright-mcp"],
      "env": {
        "CDP_ENDPOINT": "http://localhost:9222"
      }
    }
  }
}

CLI Options

ultimate-playwright-mcp [options]

Options:
  --cdp-endpoint <url>  CDP endpoint URL (e.g., http://localhost:9222)
                        Can also use CDP_ENDPOINT env var.
                        If omitted, daemon-managed Chrome is started lazily on first tool call.
  --agent-id <id>       Optional agent ID for logging/debugging
                        Can also use AGENT_ID env var
  --keep-alive          Auto-restart daemon-managed Chrome if it exits
                        Use --no-keep-alive for testing workflows where you want Chrome to stay down after kill
                        Default: disabled (no auto-restart)
                        Can also use KEEP_ALIVE env var (set to "false" to disable)
  --checkpoint-output-dir <path>
                        Root directory for checkpoint manifests, artifacts, and reports
                        Can also use CHECKPOINT_OUTPUT_DIR env var
  -V, --version         Output version number
  -h, --help            Display help

Multi-Agent Setup

Running Multiple Claude Code Instances

Each instance connects to the same MCP server and gets isolated tabs:

Terminal 1:

claude-code --mcp-config ./mcp-config.json
# Agent A creates tabs with targetIds starting from ABC...

Terminal 2:

claude-code --mcp-config ./mcp-config.json
# Agent B creates tabs with targetIds starting from XYZ...

Both agents share cookies and sessions but operate on different tabs!

Persistent Chrome Setup (macOS)

For a Chrome instance that auto-starts with debug port:

Create ~/Library/LaunchAgents/com.user.chrome-debug.plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>com.user.chrome-debug</string>
    <key>ProgramArguments</key>
    <array>
        <string>/Applications/Google Chrome.app/Contents/MacOS/Google Chrome</string>
        <string>--remote-debugging-port=9222</string>
        <string>--user-data-dir=/Users/YOUR_USERNAME/chrome-debug-profile</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
    <key>KeepAlive</key>
    <true/>
</dict>
</plist>

Load with:

launchctl load ~/Library/LaunchAgents/com.user.chrome-debug.plist

Development

# Install dependencies
npm install

# Build
npm run build

# Type check
npm run type-check

# Lint
npm run lint

# Watch mode
npm run watch

License

MIT

Attribution

This project extracts browser control code from OpenClaw (MIT licensed), which provides battle-tested tab isolation and Playwright integration.

Key extracted components:

• CDP session management (pw-session.ts)
• Browser operations (pw-tools-*.ts)
• Role-based element refs (pw-role-snapshot.ts)

Links

• OpenClaw - Source of browser control code
• MCP Specification - Model Context Protocol
• Playwright - Browser automation library