Technical SEO

Core Web Vitals Analyzer

/cwv-check

Analyze Core Web Vitals (LCP, INP, CLS) for any page and get actionable fix recommendations. Uses CrUX data and lab metrics for a complete performance picture.

Get this skill

Install all free SEO skills with one command:

curl -fsSL https://raw.githubusercontent.com/ccforseo/seo-skills/main/install.sh | bash

Or install this skill manually:

$ git clone https://github.com/ccforseo/seo-skills.git
$ cp -r seo-skills/core-web-vitals ~/.claude/skills/core-web-vitals
View on GitHubFree · MIT License · 8 skills included

What it does

The Core Web Vitals Analyzer skill checks Largest Contentful Paint, Interaction to Next Paint, and Cumulative Layout Shift for any URL. It pulls real-user data from the Chrome UX Report API when available and supplements with lab measurements. Each metric comes with a pass/fail rating and specific code-level recommendations to improve scores.

Key features

  • Measures LCP, INP, and CLS against Google thresholds
  • Pulls real-user data from the Chrome UX Report (CrUX) API
  • Identifies specific elements causing poor scores
  • Provides code-level fix recommendations per metric
  • Compares mobile and desktop performance separately

How to use Core Web Vitals Analyzer

  1. Run the command

    Type /cwv-check followed by the URL you want to analyze. Add --mobile or --desktop to test a specific viewport.

  2. Review the metrics

    The output shows each Core Web Vital with its value, threshold status (good/needs improvement/poor), and the HTML element responsible.

  3. Apply the fixes

    Follow the specific recommendations for each failing metric. The skill provides code snippets and configuration changes you can apply directly.

When to use it

Diagnosing pages that fail CWV in Google Search Console

Pre-launch performance validation

Monitoring CWV after deploying code changes

Comparing performance across competitor pages

Frequently asked questions

What is the difference between lab data and field data for Core Web Vitals?

Lab data comes from simulated page loads in a controlled environment, useful for debugging. Field data reflects real user experiences collected by Chrome. This skill uses both: CrUX field data when available and lab measurements for detailed diagnostics.

How often should I check Core Web Vitals?

Run checks after every deployment that changes page layout or loading behavior. Monthly checks catch regressions from third-party scripts or content changes. Google updates CrUX data every 28 days.

Can the Core Web Vitals Analyzer test pages behind a login?

Lab measurements work on any accessible page, including authenticated ones if you provide session credentials. CrUX field data is only available for publicly accessible URLs with enough traffic volume.

What LCP score should I target for good SEO performance?

Google considers LCP under 2.5 seconds as good. Between 2.5-4 seconds is needs improvement. Above 4 seconds is poor. Aim for under 2.0 seconds to stay comfortably in the green zone.

Related skills

Technical SEO

Site Audit

/seo-audit

Run a full technical SEO audit from your terminal. Checks crawlability, indexation issues, meta tags, page speed signals, and site structure in one pass.

Data & Analytics

Landing Page Audit

/lp-audit

Audit landing page performance combining SEO, UX, and conversion metrics. Identifies why pages underperform in traffic, engagement, or conversions.

Technical SEO

Broken Link Checker

/broken-links

Find all broken internal and external links on your site. Reports 404s, 5xx errors, timeout links, and redirect chains with their source pages.

Content SEO

Content Readability Scorer

/readability

Score your content's readability using Flesch-Kincaid, sentence length analysis, and paragraph structure checks. Get specific suggestions to improve scannability.

Get all 50 skills

The SEO Command Center includes every skill in this library plus Python data fetchers, CLAUDE.md configs, and report templates. One-time purchase.

Browse all skills