How to Check Core Web Vitals with Claude (PageSpeed Insights MCP)

Core Web Vitals affect your rankings. Google made that clear. LCP, INP, CLS. These metrics matter for search and user experience.

Checking them manually means running PageSpeed Insights one URL at a time. Copy URL, run test, note scores, repeat. For a site with hundreds of pages, that's not realistic.

This guide shows how to check Core Web Vitals for many pages at once with Claude and the hosted PageSpeed Insights MCP server, and how to turn the results into fixes.

"What's the LCP score for my top landing pages?" Just ask.

What Is the PageSpeed Insights MCP Server

The PageSpeed Insights MCP server uses Model Context Protocol to give Claude Google Lighthouse results for any public URL.

MCP is Anthropic's open standard for connecting AI to external data sources. Instead of manually running tests, you ask Claude questions. Claude runs a Lighthouse test and analyzes the results.

For developers and SEO teams, this means bulk performance testing without the tedious manual process.

What Data You Can Access

The PageSpeed Insights MCP server provides comprehensive performance data.

Core Web Vitals:

• Largest Contentful Paint (LCP)

• Interaction to Next Paint (INP), from Chrome UX Report field data when Google has it for the page

• Cumulative Layout Shift (CLS)

• First Contentful Paint (FCP)

• Time to First Byte (TTFB)

Performance Scores:

• Overall performance score (0-100)

• Accessibility score

• Best practices score

• SEO score

Lab Data:

• Speed Index

• Total Blocking Time

• Time to Interactive (a legacy Lighthouse metric)

• Lighthouse metrics

Field Data:

• Chrome User Experience Report (CrUX) data

• Real user metrics when available

• Origin-level vs. URL-level data

Optimization Opportunities:

• Specific recommendations

• Estimated savings per fix

• Resource-level details

Use Cases

Audit Core Web Vitals Across Key Pages

Your homepage might score well. But what about your product pages, blog posts, and landing pages?

Ask Claude: "Check Core Web Vitals for my top 10 landing pages. Which ones fail Google's thresholds? What's causing the issues?"

Get a multi-page performance picture without running tests one by one.

Diagnose LCP Problems

Largest Contentful Paint measures loading performance. When it's slow, users leave before your page renders.

"My homepage LCP is 4.2 seconds. What's the largest element? What specific changes would improve it?"

Claude can identify the bottleneck and suggest fixes.

Track CLS Issues

Cumulative Layout Shift measures visual stability. Unexpected layout jumps frustrate users and hurt rankings.

"Which of my pages have CLS problems? What elements are shifting and why?"

Find the unstable elements causing layout shifts.

Compare Desktop vs. Mobile

Performance often differs between devices. Mobile users typically face worse conditions.

"How does my site's mobile performance compare to desktop? Which metrics show the biggest gap?"

Understand where mobile optimization needs work.

How to Set Up

Setup takes a few minutes. InsightfulPipe hosts the server, so there's nothing to install.

1. Create an InsightfulPipe account (7-day trial).

2. Copy the server URL: https://pagespeed-insights.insightfulmcp.com/

3. In Claude, open Settings → Connectors, click Add custom connector, paste the URL and click Add.

4. Click Connect, then Authorize access in the browser.

5. Start a new chat, turn the connector on, and ask: "What are the Core Web Vitals for my homepage on mobile?"

Using Claude Code? Run claude mcp add --transport http pagespeed-insights-mcp https://pagespeed-insights.insightfulmcp.com/, then type /mcp and authenticate. Steps for ChatGPT, Cursor, Gemini CLI and Codex CLI are on the PageSpeed Insights MCP server page.

Example Queries

Once connected, you can ask Claude:

• "What are the Core Web Vitals for my homepage on mobile?"

• "Which of my product pages have LCP above 2.5 seconds?"

• "What's causing layout shift on my blog pages? How do I fix it?"

• "Compare performance between my old landing page and new landing page."

• "What's the estimated performance gain if I implement lazy loading on my product images?"

• "How does my site's TTFB compare between different pages? Is there a server-side issue?"

Include specific URLs or page types for the most useful results.

Common Questions

Does this test live pages or cached versions?

Each request runs a fresh Lighthouse test on the live page. Lab scores can vary a few points between runs, so re-test before acting on small differences.

What's the difference between lab data and field data?

Lab data comes from simulated tests (Lighthouse). Field data comes from real Chrome users (CrUX). Field data requires sufficient traffic to your pages.

Can I test pages behind login?

PageSpeed Insights tests publicly accessible pages. For authenticated pages, you'd need different testing approaches.

How accurate are the optimization estimates?

Estimates are directional. "Savings of 1.2s" means the fix would help, but actual improvement depends on implementation details.

Can I test competitor pages?

Yes. PageSpeed Insights works on any public URL. You can analyze competitor performance for benchmarking.

Start Optimizing Your Performance

Page speed affects rankings, conversions, and user experience. Core Web Vitals are now a ranking factor. Slow sites lose traffic.

The PageSpeed Insights MCP server makes performance testing accessible. Ask questions, identify problems, get recommendations.

Ready to connect PageSpeed Insights to Claude? Get the PageSpeed Insights MCP server and start optimizing your Core Web Vitals today.

Plans start at $29.99/month with a 7-day trial, and every plan includes all hosted MCP servers and the CLI.

More prompts: the resource optimization report prompt and 50 SEO prompts for Claude.