snqb/seo

SEO — Unified Audit & Fix Skill

One skill, eight domains. Audit what exists, fix what's broken, generate what's missing.

Quick Start

"Audit SEO for this site"         → Full audit (all 8 domains)
"Check this page's SEO"           → Single-page deep analysis
"Generate schema for this page"   → JSON-LD structured data
"Fix my sitemap"                  → Sitemap validation + generation
"Why isn't this page ranking?"    → On-page + technical diagnosis

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1. Technical Audit

Score each category, flag issues by severity (Critical / High / Medium / Low).

1.1 Crawlability

• robots.txt: exists, valid syntax, sitemap declared, no accidental blocks
• XML sitemap: valid, <50K URLs per file, referenced in robots.txt
• Crawl depth: important pages within 3 clicks of homepage
• Crawl budget: for large sites — duplicate/thin content wastes budget
• JS rendering: is critical content in initial HTML or behind JS?

AI Crawler Management (2025–2026):

| Crawler | Company | Token | Purpose | |---------|---------|-------|---------| | GPTBot | OpenAI | GPTBot | Training | | ChatGPT-User | OpenAI | ChatGPT-User | Browsing | | ClaudeBot | Anthropic | ClaudeBot | Training | | Google-Extended | Google | Google-Extended | Gemini training (NOT search) | | PerplexityBot | Perplexity | PerplexityBot | Search + training | | Bytespider | ByteDance | Bytespider | Training |

Blocking Google-Extended does NOT affect Google Search or AI Overviews — those use Googlebot.

1.2 Indexability

• Canonical tags: present, self-referencing, no conflicts with noindex
• Duplicate content: near-duplicates, parameter URLs, www/non-www, http/https
• Index blockers: noindex meta, noindex X-Robots-Tag, robots.txt blocked, canonical to other
• Thin content: pages below minimum word count for their type
• Index bloat: unnecessary pages in index consuming crawl budget

JS SEO (Dec 2025 Google update):

• If raw HTML canonical differs from JS-injected canonical, Google may use either
• noindex in raw HTML may be honored even if JS removes it
• Google does NOT render JS on non-200 pages
• Serve critical SEO elements (canonical, meta robots, structured data, title) in initial server HTML

1.3 Core Web Vitals

Evaluation uses 75th percentile of real user data.

| Metric | Good | Needs Work | Poor | |--------|------|------------|------| | LCP (Largest Contentful Paint) | <2.5s | 2.5–4s | >4s | | INP (Interaction to Next Paint) | <200ms | 200–500ms | >500ms | | CLS (Cumulative Layout Shift) | <0.1 | 0.1–0.25 | >0.25 |

INP replaced FID on March 12, 2024. Never reference FID.

Use PageSpeed Insights API if available:

https://www.googleapis.com/pagespeedonline/v5/runPagespeed?url=URL&strategy=mobile

1.4 Security

• HTTPS enforced, valid SSL, no mixed content
• HSTS header with includeSubDomains
• Security headers: CSP, X-Frame-Options, X-Content-Type-Options, Referrer-Policy
• Check HSTS preload list for high-security sites

1.5 URL Structure

• Clean: descriptive, hyphenated, lowercase, no query params for content
• Hierarchy: logical folder structure reflecting site architecture
• Redirects: no chains (max 1 hop), 301 for permanent
• Length: flag >100 chars
• Trailing slashes: consistent

1.6 Mobile

Mobile-first indexing is 100% complete (July 2024). Google crawls ALL sites with mobile Googlebot.

• Responsive: viewport meta, responsive CSS
• Touch targets: minimum 48×48px, 8px spacing
• Font size: minimum 16px base
• No horizontal scroll
• Test: does content match between mobile and desktop?

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2. On-Page Analysis

2.1 Title Tag

• Length: 50–60 characters (Google truncates at ~60)
• Contains primary keyword near front
• Unique per page, not duplicated
• Compelling — optimized for CTR, not just keywords
• Brand: append brand name with | separator (e.g., Primary Keyword | Brand)

2.2 Meta Description

• Length: 120–160 characters
• Contains primary keyword (Google bolds matches)
• Includes call-to-action or value proposition
• Unique per page
• Not auto-generated placeholder text

2.3 Headings

• Exactly one <h1> per page, matches page intent
• H2–H6 logical hierarchy (no skipped levels)
• Headings are descriptive, not generic ("Section 1")
• Primary keyword in H1, secondary keywords in H2s

2.4 Content Quality

• Word count appropriate for page type (blog: 1500+, product: 300+, landing: 500+)
• Readability: grade level appropriate for audience
• Keyword density: 1–3%, with semantic variations
• E-E-A-T signals: author bio, credentials, experience markers, dates
• Freshness: publication + last-updated dates visible

2.5 Open Graph & Twitter Cards

<meta property="og:type" content="website" />
<meta property="og:title" content="Title (70 chars max)" />
<meta property="og:description" content="Description (200 chars max)" />
<meta property="og:image" content="https://example.com/image.jpg" />  <!-- 1200×630px -->
<meta property="og:url" content="https://example.com/page" />
<meta property="og:locale" content="ru_RU" />
<meta name="twitter:card" content="summary_large_image" />

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3. Images

Alt Text

• Present on all <img> (except decorative: role="presentation")
• Descriptive: describes content, not "image.jpg"
• 10–125 characters, includes keywords where natural

File Size Targets

| Category | Target | Warning | Critical | |----------|--------|---------|----------| | Thumbnails | <50KB | >100KB | >200KB | | Content | <100KB | >200KB | >500KB | | Hero/banner | <200KB | >300KB | >700KB |

Format Priority

1. AVIF (93.8% support) — best compression
2. WebP (95.3% support) — safe default
3. JPEG/PNG — fallback only

<picture>
  <source srcset="image.avif" type="image/avif">
  <source srcset="image.webp" type="image/webp">
  <img src="image.jpg" alt="Description" width="800" height="600" loading="lazy" decoding="async">
</picture>

Loading Strategy

• Hero/LCP image: fetchpriority="high", NO loading="lazy"
• Below-fold images: loading="lazy" + decoding="async"
• All images: explicit width + height (prevents CLS)

File Names

• Descriptive: blue-running-shoes.webp not IMG_1234.jpg
• Lowercase, hyphenated, no special characters

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4. Structured Data (JSON-LD)

JSON-LD is Google's preferred format. Serve in initial HTML, not injected via JS.

Active Types (recommend freely)

Organization, LocalBusiness, Product, ProductGroup, Offer, Service, Article, BlogPosting, NewsArticle, Review, AggregateRating, BreadcrumbList, WebSite, WebPage, Person, ProfilePage, VideoObject, ImageObject, Event, JobPosting, Course, SoftwareApplication, TravelGuide

Restricted / Deprecated

• FAQ: ONLY for government/healthcare sites (restricted Aug 2023)
• HowTo: Rich results removed Sep 2023 — never recommend
• SpecialAnnouncement: Deprecated Jul 2025
• FID-related: FID fully removed Sep 2024

Validation Checklist

• [ ] @context: https://schema.org
• [ ] @type: valid, active type
• [ ] All required properties present
• [ ] URLs are absolute (not relative)
• [ ] Dates in ISO 8601 format
• [ ] No placeholder text
• [ ] Consistent with visible page content (Google penalizes mismatch)

Common Templates

Organization:

{
  "@context": "https://schema.org",
  "@type": "Organization",
  "name": "",
  "url": "",
  "logo": "",
  "contactPoint": { "@type": "ContactPoint", "telephone": "", "contactType": "customer service" },
  "sameAs": ["", ""]
}

LocalBusiness:

{
  "@context": "https://schema.org",
  "@type": "LocalBusiness",
  "name": "", "url": "", "telephone": "",
  "address": { "@type": "PostalAddress", "streetAddress": "", "addressLocality": "", "addressCountry": "" },
  "geo": { "@type": "GeoCoordinates", "latitude": "", "longitude": "" },
  "openingHoursSpecification": [{ "@type": "OpeningHoursSpecification", "dayOfWeek": ["Mo","Tu","We","Th","Fr"], "opens": "09:00", "closes": "18:00" }]
}

BreadcrumbList:

{
  "@context": "https://schema.org",
  "@type": "BreadcrumbList",
  "itemListElement": [
    { "@type": "ListItem", "position": 1, "name": "Home", "item": "https://example.com" },
    { "@type": "ListItem", "position": 2, "name": "Category", "item": "https://example.com/cat" },
    { "@type": "ListItem", "position": 3, "name": "Page" }
  ]
}

Article:

{
  "@context": "https://schema.org", "@type": "Article",
  "headline": "", "author": { "@type": "Person", "name": "" },
  "datePublished": "", "dateModified": "",
  "image": "", "publisher": { "@type": "Organization", "name": "", "logo": { "@type": "ImageObject", "url": "" } }
}

Product + Offer:

{
  "@context": "https://schema.org", "@type": "Product",
  "name": "", "image": "", "description": "",
  "brand": { "@type": "Brand", "name": "" },
  "offers": { "@type": "Offer", "url": "", "priceCurrency": "USD", "price": "", "availability": "https://schema.org/InStock" }
}

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5. Sitemaps

Validation

• Valid XML, <50K URLs per file
• All URLs return HTTP 200
• No noindexed, redirected, or non-canonical URLs
• <lastmod> dates are real (not all identical/current timestamp)
• <priority> and <changefreq> are ignored by Google — can omit
• Referenced in robots.txt
• Compare crawled pages vs sitemap — flag missing pages

Generation Rules

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <url>
    <loc>https://example.com/page</loc>
    <lastmod>2026-03-11</lastmod>
  </url>
</urlset>

For >50K URLs, use sitemap index:

<?xml version="1.0" encoding="UTF-8"?>
<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <sitemap><loc>https://example.com/sitemap-pages.xml</loc></sitemap>
  <sitemap><loc>https://example.com/sitemap-posts.xml</loc></sitemap>
</sitemapindex>

Penalty Risks at Scale

• Location pages with only city name swapped
• "[Competitor] alternative" without real comparison data
• AI-generated pages without unique value

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6. Hreflang & International SEO

Implementation Methods

1. HTML <link> tags — simple, <50 language versions
2. HTTP headers — for non-HTML files (PDFs)
3. XML sitemap — recommended for large/cross-domain setups

Validation Checklist

• [ ] Self-referencing: every page hreflang-links to itself
• [ ] Bidirectional: if A→B exists, B→A must exist
• [ ] x-default: designates fallback for unmatched languages
• [ ] Language codes: ISO 639-1 (en, ru, ja — NOT eng, jp)
• [ ] Region codes: ISO 3166-1 Alpha-2 (en-US, en-GB, pt-BR — NOT en-uk)
• [ ] Canonical alignment: hreflang only on canonical URLs
• [ ] Protocol consistency: all HTTPS or all HTTP, never mixed
• [ ] URL match: hreflang URLs match canonical URLs exactly (trailing slash, params)

Common Mistakes

| Issue | Severity | |-------|----------| | Missing self-referencing tag | Critical | | Missing return tags (A→B but no B→A) | Critical | | Missing x-default | High | | Invalid language code (eng instead of en) | High | | Invalid region code (en-uk instead of en-GB) | High | | Hreflang on non-canonical URL | High | | zh without region qualifier | Medium | | Hreflang route doesn't exist (404) | Critical |

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7. Internal Linking

Audit

• Orphan pages: no internal links pointing to them — invisible to crawlers
• Link distribution: average links per page, identify extremes
• Under-linked important pages: high-traffic pages with few inlinks
• Anchor text: descriptive, keyword-relevant (not "click here")
• Broken internal links: 404s waste crawl budget and link equity
• Nofollow on internal links: almost never appropriate

Best Practices

• Every page reachable within 3 clicks from homepage
• Hub-and-spoke: pillar pages link to clusters, clusters link back
• Contextual links in body content > nav/footer links
• Distribute link equity to revenue/conversion pages
• New content should be linked from existing high-authority pages

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8. Audit Output Format

Score Card

Overall: XX/100

Technical:        XX/100  ████████░░
On-Page:          XX/100  ██████████
Images:           XX/100  ███████░░░
Structured Data:  XX/100  █████░░░░░
Sitemap:          XX/100  ████████░░
Hreflang:         XX/100  ██████░░░░
Internal Links:   XX/100  ████████░░

Issue Triage

1. Critical (fix immediately): blocks indexing or causes penalties
2. High (fix within 1 week): significantly hurts rankings
3. Medium (fix within 1 month): missed opportunities
4. Low (backlog): minor optimizations

Prioritized Fix Table

| # | Fix | Effort | Impact | Domain | |---|-----|--------|--------|--------| | 1 | ... | Low/Med/High | 🔴🔴🔴 | Technical | | 2 | ... | Low | 🟠🟠 | On-Page |

For Each Fix

• What: specific problem with affected URLs/elements
• Why: SEO impact explained
• How: code snippet or step-by-step fix
• Verify: how to confirm the fix worked

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Tools

PageSpeed Insights API (free, no key)

curl -s "https://www.googleapis.com/pagespeedonline/v5/runPagespeed?url=URL&strategy=mobile" | jq '.lighthouseResult.categories'

Check robots.txt

curl -s https://example.com/robots.txt

Check sitemap

curl -s https://example.com/sitemap.xml | head -50

Validate structured data

# Extract JSON-LD from page
curl -s URL | grep -oP '<script type="application/ld\+json">\K[^<]+'

Check HTTP headers

curl -sI https://example.com/ | grep -iE "x-frame|x-content|strict-transport|referrer-policy|content-security|cache-control"

Verify hreflang

curl -s URL | grep -i hreflang

Count internal links

curl -s URL | grep -oE 'href="https?://example\.com[^"]*"' | sort -u | wc -l

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Sources

Fused from: aaron-he-zhu/seo-geo-claude-skills (20 skills, 807+ installs), agricidaniel/claude-seo (14 skills, 111+ installs), seo-skills/seo-audit-skill (257 installs). Distilled to actionable checklists; removed filler, duplicate cross-references, and tool-specific integrations.