webperf-core-web-vitals

Intelligent Core Web Vitals analysis with automated workflows and decision trees. Measures LCP, CLS, INP with guided debugging that automatically determines follow-up analysis based on results. Includes workflows for LCP deep dive (5 phases), CLS investigation (loading vs interaction), INP debugging (latency breakdown + attribution), and cross-skill integration with loading, interaction, and media skills. Use when the user asks about Core Web Vitals, LCP optimization, layout shifts, or interaction responsiveness. Compatible with Chrome DevTools MCP.

Try your first task

Measure a page's LCP

Start a fresh conversation.

Use webperf-core-web-vitals to measure Largest Contentful Paint on <url> with LCP.js. Report the returned value, rating, and any reported issues. If measurement is unsupported or fails, explain the returned error.

Required inputs

Replace <url> with the page URL to measure.
Configure Chrome DevTools MCP, or install the documented CLI with Playwright and Chromium.

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