our-claude-skills/custom-skills/15-seo-core-web-vitals/desktop/SKILL.md

name, description, allowed-tools

name	description	allowed-tools
seo-core-web-vitals	Core Web Vitals analyzer for LCP, FID, CLS, INP performance metrics. Triggers: Core Web Vitals, page speed, LCP, CLS, FID, INP, performance.	mcp__firecrawl__*, mcp__perplexity__*

SEO Core Web Vitals

Purpose

Analyze Core Web Vitals performance metrics and provide optimization recommendations.

Core Capabilities

1. LCP - Largest Contentful Paint measurement
2. FID/INP - Interactivity metrics
3. CLS - Cumulative Layout Shift
4. Recommendations - Optimization guidance

Metrics Thresholds

Metric	Good	Needs Work	Poor
LCP	≤2.5s	2.5-4s	>4s
FID	≤100ms	100-300ms	>300ms
CLS	≤0.1	0.1-0.25	>0.25
INP	≤200ms	200-500ms	>500ms

Data Sources

Option 1: PageSpeed Insights (Recommended)

Use external tool and input results:

• Visit: https://pagespeed.web.dev/
• Enter URL, run test
• Provide scores to skill

Option 2: Research Best Practices

mcp__perplexity__search: "Core Web Vitals optimization [specific issue]"

Workflow

1. Request PageSpeed Insights data from user
2. Analyze provided metrics
3. Identify failing metrics
4. Research optimization strategies
5. Provide prioritized recommendations

Common LCP Issues

Cause	Fix
Slow server response	Improve TTFB, use CDN
Render-blocking resources	Defer non-critical CSS/JS
Slow resource load	Preload LCP image
Client-side rendering	Use SSR/SSG

Common CLS Issues

Cause	Fix
Images without dimensions	Add width/height attributes
Ads/embeds without space	Reserve space with CSS
Web fonts causing FOIT/FOUT	Use font-display: swap
Dynamic content injection	Reserve space, use transforms

Common INP Issues

Cause	Fix
Long JavaScript tasks	Break up tasks, use web workers
Large DOM size	Reduce DOM nodes
Heavy event handlers	Debounce, optimize listeners
Third-party scripts	Defer, lazy load

Output Format

## Core Web Vitals: [URL]

### Scores
| Metric | Mobile | Desktop | Status |
|--------|--------|---------|--------|
| LCP | Xs | Xs | Good/Poor |
| FID | Xms | Xms | Good/Poor |
| CLS | X.XX | X.XX | Good/Poor |
| INP | Xms | Xms | Good/Poor |

### Overall Score
- Mobile: X/100
- Desktop: X/100

### Priority Fixes
1. [Highest impact recommendation]
2. [Second priority]

### Detailed Recommendations
[Per-metric optimization steps]

Limitations

• Requires external PageSpeed Insights data
• Lab data may differ from field data
• Some fixes require developer implementation
• Third-party scripts may be difficult to optimize

Notion Output (Required)

All audit reports MUST be saved to OurDigital SEO Audit Log:

• Database ID: 2c8581e5-8a1e-8035-880b-e38cefc2f3ef
• Properties: Issue (title), Site (url), Category, Priority, Found Date, Audit ID
• Language: Korean with English technical terms
• Audit ID Format: [TYPE]-YYYYMMDD-NNN