Playwright MCP Browser Setup

Each project workspace configures its own Playwright MCP browser sessions in a .mcp.json file at the project root. The Nextcloud workspace uses 7 browsers; other workspaces may use fewer depending on the parallelism their tests demand. An example .mcp.json with the 7-browser configuration is available as a starting point.

Browser Pool (Nextcloud workspace)

Server	Mode	Purpose
browser-1	Headless	Main agent (default)
browser-2	Headless	Sub-agent / parallel
browser-3	Headless	Sub-agent / parallel
browser-4	Headless	Sub-agent / parallel
browser-5	Headless	Sub-agent / parallel
browser-6	Headed	User observation (visible window)
browser-7	Headless	Sub-agent / parallel

VS Code Extension Setup

The VS Code extension loads MCP servers from .mcp.json in the project root (this file lives in each project repo, not in the .github documentation repo). The file defines 7 browser instances. Browsers 1–5 and 7 are headless; browser-6 is headed (omits --headless) so the browser window is visible when you want to watch:

{
  "mcpServers": {
    "browser-1": { "command": "npx", "args": ["-y", "@playwright/mcp@latest", "--browser", "chromium", "--headless", "--isolated"] },
    "browser-2": { "command": "npx", "args": ["-y", "@playwright/mcp@latest", "--browser", "chromium", "--headless", "--isolated"] },
    "browser-3": { "command": "npx", "args": ["-y", "@playwright/mcp@latest", "--browser", "chromium", "--headless", "--isolated"] },
    "browser-4": { "command": "npx", "args": ["-y", "@playwright/mcp@latest", "--browser", "chromium", "--headless", "--isolated"] },
    "browser-5": { "command": "npx", "args": ["-y", "@playwright/mcp@latest", "--browser", "chromium", "--headless", "--isolated"] },
    "browser-6": { "command": "npx", "args": ["-y", "@playwright/mcp@latest", "--browser", "chromium", "--isolated"] },
    "browser-7": { "command": "npx", "args": ["-y", "@playwright/mcp@latest", "--browser", "chromium", "--headless", "--isolated"] }
  }
}

The project's shared .claude/settings.json has two pre-approval entries:

• "enableAllProjectMcpServers": true — auto-approves all servers from .mcp.json without prompting on each reload.
• All mcp__browser-* tool calls — pre-approved for all 7 browsers so that parallel sub-agents (used by /test-app Full mode and /test-counsel) can use their assigned browser without needing an interactive permission prompt. Without this, background agents are silently denied and no testing occurs.

Then reload the VS Code window: Ctrl+Shift+P → type reload window → Enter.

Verification

After reload, open the MCP servers panel to verify all 7 browsers show Connected. You can do this two ways:

• Type /MCP servers in the Claude Code chat input
• Or Ctrl+Shift+P → search "MCP servers"

If any server shows an error, check the output panel: Ctrl+Shift+P → "Output: Focus on Output" → select "Claude VSCode" from the dropdown.

CLI Alternative (terminal only)

For the Claude Code CLI (claude terminal command, not VS Code), you can start servers as HTTP endpoints on fixed ports and reference them via URL:

# Start headless browsers
for port in 9221 9222 9223 9224 9225 9227; do
  npx -y @playwright/mcp@latest --headless --isolated --port $port &
done

# Start headed browser
npx -y @playwright/mcp@latest --isolated --port 9226 &

This is not needed for VS Code — the extension manages server processes automatically via .mcp.json. Only use this approach if you're running claude from the terminal without VS Code.

Usage Rules

1. Default: Use browser-1 for normal work
2. Parallel agents: Assign sub-agents browser-2 through browser-5 and browser-7
3. User watching: Switch to browser-6 when the user wants to observe
4. Fallback: If a browser errors, try the next numbered browser
5. Keep browser-6 reserved: Only for explicit user observation