Playwriter MCP

Playwriter MCP Guide

ACTIVATION: Only use when user explicitly says "Playwriter". Default browser MCP is ms-playwright-mcp by Microsoft.

Rules and usage for Playwriter - Chrome extension + CLI/MCP for real browser automation.

Table of Contents

Core

• When to Use
• Intent Lookup
• MUST-NOT-FORGET

Workflows

• Quick Start
• Common Workflows
• Screenshots
• Visual Labels
• Screen Recording

Reference

• CLI Commands
• MCP Configuration
• Troubleshooting
• Security
• Setup - Installation

When to Use Playwriter (vs Playwright MCP)

Use Playwriter when:

• Need existing logged-in sessions (bank, email, social media)
• Want to use your ad blockers, password managers, extensions
• Avoiding automation/bot detection
• Collaborating with AI in real-time (you see what it does)

Use Playwright MCP when:

• Need clean, isolated sessions
• Testing without user state
• Standard automation without auth requirements

Intent Lookup

User wants to...

• Check bank account / pay bills -> Existing session, visual labels, snapshot({ page })
• Read email / send messages -> Existing Gmail/Outlook session, no re-auth
• Post to social media -> Bypass bot detection, use existing cookies
• Fill government forms -> Use saved passwords, extensions
• Scrape authenticated content -> No login needed, existing cookies
• Debug web app -> getCDPSession, createDebugger, breakpoints
• Record demo/tutorial -> startRecording / stopRecording
• Collaborate with AI -> Real-time visibility, can intervene

Technical tasks...

• Get element refs -> snapshot({ page }) or screenshotWithAccessibilityLabels({ page })
• Take screenshot -> page.screenshot({ path: '...', type: 'jpeg' })
• Click by ref -> page.locator('aria-ref=e5').click()
• Persist data -> state.varName = ...
• Intercept API -> page.on('response', ...)
• Record session -> startRecording / stopRecording

MUST-NOT-FORGET

• Install Chrome extension FIRST (from Chrome Web Store)
• Click extension icon on tab to enable control (icon turns green)
• Use single quotes for -e to prevent bash interpretation
• Never call browser.close() - it closes YOUR Chrome
• Use state.varName to persist data between calls
• Green icon = connected, gray = not controlled
• TIMEOUTS: ALWAYS pass timeout (default 20000ms is too long!). Use 1500 for simple ops, 3000 for screenshots.
• NO waitForTimeout inside code - causes stalls. Use proper waits like waitForSelector instead.
• goto() stalls on SPAs - default waitUntil: 'load' never fires on SharePoint/dynamic sites. Use { waitUntil: 'domcontentloaded' }.
• click() can stall - if element triggers animation/loading that blocks. Don't click multiple elements in one call.
• After any cancellation - always check connection before proceeding with more operations.
• If stalled, reset won't work - user must restart Chrome or click extension icon again.

Quick Start

# 1. Install CLI
npm i -g playwriter

# 2. Create session
playwriter session new  # outputs ID (e.g., 1)

# 3. Navigate
playwriter -s 1 -e 'await page.goto("https://example.com")'

# 4. Get accessibility snapshot
playwriter -s 1 -e 'console.log(await snapshot({ page }))'

# 5. Click element by ref
playwriter -s 1 -e 'await page.locator("aria-ref=e5").click()'

CLI Commands

Session Management

playwriter session new          # Create sandbox, get ID
playwriter session list         # Show sessions + state keys
playwriter session reset <id>   # Fix connection issues

Execute Code

playwriter -s <id> -e '<code>'  # Run Playwright code in session

Variables in scope: page, context, state, require

Common Workflows

Navigate and Screenshot

playwriter -s 1 -e 'await page.goto("https://example.com")'
playwriter -s 1 -e 'await page.screenshot({ path: "screenshot.png" })'

Screenshot with Visual Labels

playwriter -s 1 -e 'await screenshotWithAccessibilityLabels({ page })'
# Returns screenshot with Vimium-style labels (aria-ref=e1, e2, etc.)
playwriter -s 1 -e 'await page.locator("aria-ref=e5").click()'

Persist Data Between Calls

playwriter -s 1 -e "state.users = await page.$$eval('.user', els => els.map(e => e.textContent))"
playwriter -s 1 -e "console.log(state.users)"

Create Isolated Page

playwriter -s 1 -e 'state.myPage = await context.newPage(); await state.myPage.goto("https://example.com")'

Intercept Network Requests

playwriter -s 1 -e "state.requests = []; page.on('response', r => { if (r.url().includes('/api/')) state.requests.push(r.url()) })"
playwriter -s 1 -e "await Promise.all([page.waitForResponse(r => r.url().includes('/api/')), page.click('button')])"
playwriter -s 1 -e "console.log(state.requests)"

Screenshots

# Basic screenshot
playwriter -s 1 -e 'await page.screenshot({ path: "screenshot.png" })'

# Full page
playwriter -s 1 -e 'await page.screenshot({ path: "full.png", fullPage: true })'

# JPEG (smaller)
playwriter -s 1 -e 'await page.screenshot({ path: "shot.jpg", type: "jpeg", quality: 80 })'

Visual Labels

Vimium-style labels for AI element identification:

playwriter -s 1 -e 'await screenshotWithAccessibilityLabels({ page })'
playwriter -s 1 -e 'await page.locator("aria-ref=e5").click()'

Color coding:

• Yellow = links
• Orange = buttons
• Coral = inputs
• Pink = checkboxes
• Peach = sliders
• Salmon = menus
• Amber = tabs

Accessibility Snapshot (No Screenshot)

playwriter -s 1 -e 'console.log(await snapshot({ page }))'
# Returns accessibility tree with aria-ref selectors

Screen Recording [ASSUMED]

# Start recording
playwriter -s 1 -e 'await startRecording({ page, outputPath: "./recording.mp4", frameRate: 30 })'

# Navigate, interact...
playwriter -s 1 -e 'await page.click("a")'

# Stop and save
playwriter -s 1 -e 'await stopRecording({ page })'

Recording survives page navigation (uses chrome.tabCapture).

MCP Configuration

Skill-based (recommended):

npx -y skills add remorses/playwriter

Direct MCP config:

{
  "mcpServers": {
    "playwriter": {
      "command": "npx",
      "args": ["playwriter@latest"]
    }
  }
}

Troubleshooting

View Logs

playwriter logfile  # Shows path to ~/.playwriter/relay-server.log

All Pages Return about:blank

Restart Chrome (known Chrome bug in chrome.debugger API).

Extension Icon Not Turning Green

1. Ensure extension installed from Chrome Web Store
2. Click directly on extension icon (not right-click menu)
3. Try playwriter session reset <id>

Connection Issues

playwriter session reset <id>

Security

• WebSocket binds to localhost:19988 only (any local process can connect; use --token for auth)
• Only tabs where you clicked extension icon are controlled
• Chrome shows automation banner on controlled tabs
• Malicious websites cannot connect

Requirements

• Chrome/Chromium browser
• Node.js 18+ with npm
• Playwriter Chrome extension (from Chrome Web Store)

See SETUP.md for installation details.