Core Web Vitals

Measure the Core Web Vitals of any page using real browser performance APIs. No signup required.

Prerequisites

• Playwright MCP (comes with Claude Code)

Trigger

• "Check Core Web Vitals for https://..."
• "How's the LCP/CLS on my site?"
• "Web vitals audit mysite.com"

Workflow

1. Navigate to the URL using mcp__playwright__browser_navigate
2. Let the page settle (mcp__playwright__browser_wait_for ~3s, or wait for network idle)
3. Collect metrics with mcp__playwright__browser_evaluate: