Playwright MCP Skill

Playwright MCP Skill

Use this skill to run Playwright MCP operations through uxc using fixed stdio endpoints.

Reuse the uxc skill for generic protocol discovery, auth/error handling, and envelope parsing rules.

Prerequisites

• uxc is installed and available in PATH.
• npx is available in PATH (Node.js installed).
• Network access for first-time @playwright/mcp package fetch.
• Browser runtime can start locally (headless mode is default in this skill).

Core Workflow (Playwright-Specific)

Endpoint candidate inputs before finalizing:

• Raw package form from docs: npx @playwright/mcp@latest
• Reliable non-interactive form: npx -y @playwright/mcp@latest
• Isolated/headless stable form (default for this skill):
  • npx -y @playwright/mcp@latest --headless --isolated
  • Shared-profile headless form (for persistent login state):
  • npx -y @playwright/mcp@latest --headless --user-data-dir ~/.uxc/playwright-profile
  • Shared-profile headed form (for interactive debug with same login state):
  • npx -y @playwright/mcp@latest --user-data-dir ~/.uxc/playwright-profile

1. Verify protocol/path from official source and probe:
   • Official source: https://github.com/microsoft/playwright-mcp
   • probe candidate endpoints with:
     • uxc "npx -y @playwright/mcp@latest --headless --isolated" -h
   • Confirm protocol is MCP stdio (protocol == "mcp" in envelope).
2. Detect auth requirement explicitly:
   • Run host help or a minimal read call and inspect envelope.
   • @playwright/mcp default flow is no OAuth/API key for local stdio use.
3. Use fixed link command by default:
   • command -v playwright-mcp-cli
   • If missing, create it:
     • uxc link playwright-mcp-cli "npx -y @playwright/mcp@latest --headless --isolated"
   • Optional shared-profile dual command setup for persistent sessions:
     • command -v playwright-mcp-headless
     • command -v playwright-mcp-ui
     • uxc link --daemon-exclusive ~/.uxc/playwright-profile playwright-mcp-headless "npx -y @playwright/mcp@latest --headless --user-data-dir ~/.uxc/playwright-profile"
     • uxc link --daemon-exclusive ~/.uxc/playwright-profile playwright-mcp-ui "npx -y @playwright/mcp@latest --user-data-dir ~/.uxc/playwright-profile"
   • playwright-mcp-cli -h
   • If command conflict is detected and cannot be safely reused, stop and ask skill maintainers to pick another fixed command name.
4. Inspect operation schema before execution:
   • playwright-mcp-cli browser_navigate -h
   • playwright-mcp-cli browser_snapshot -h
   • playwright-mcp-cli browser_click -h
5. Prefer read-first interaction:
   • Start with navigation/snapshot before mutating page state.
6. Execute actions with explicit confirmation when impact is high:
   • Confirm before form submission, checkout, delete/destructive actions, or irreversible multi-step flows.

Guardrails

• Keep automation on JSON output envelope; do not rely on --text.
• Parse stable fields first: ok, kind, protocol, data, error.
• Use playwright-mcp-cli as default command path.
• playwright-mcp-cli <operation> ... is equivalent to uxc "npx -y @playwright/mcp@latest --headless --isolated" <operation> ....
• Use direct uxc "<endpoint>" ... only as temporary fallback when link setup is unavailable.
• If browser profile conflict appears, keep --isolated in endpoint and retry via the same fixed link command.
• When using shared --user-data-dir, run headless/headed links serially (not concurrently).
• To enable seamless switching between headed UI login and headless CLI automation using the same profile directory, set a daemon exclusive key:
  • Prefer link-level setup (recommended above), or set UXC_DAEMON_EXCLUSIVE=~/.uxc/playwright-profile for ad-hoc runs.
  • If the profile is still busy (another session is actively running), fallback: uxc daemon stop
• Prefer browser_snapshot over screenshots for model-action loops.

References

• Invocation patterns:
  • references/usage-patterns.md