seo-technical

---
name: seo-technical
description: >
license: MIT
---

# Technical SEO Audit

## Categories

### 1. Crawlability
- robots.txt: exists, valid, not blocking important resources
- XML sitemap: run `claude-seo run sitemap_discovery.py <url> --json`; require a
  valid entry in `found`, and report stale or unsafe robots.txt declarations
  separately from working fallback locations
- Noindex tags: intentional vs accidental
- Crawl depth: important pages within 3 clicks of homepage
- JavaScript rendering: check if critical content requires JS execution
- Crawl budget: for large sites (>10k pages), efficiency matters
- Googlebot **fetch limits**: Googlebot fetches the first **2MB of HTML** and first **64MB of a PDF** (uncompressed; 15MB is the broader crawler-infra default). Long-standing, not a 2026 change, but inline base64 images, oversized inline CSS/JS, or bloated nav can push critical content/JSON-LD past the cap and out of the index. Keep key content + structured data within the first 2MB.
- Crawl rate **auto-adjusts** (backs off on 5xx/slow responses); there is **no manual crawl-rate control** (the legacy Search Console setting was removed Jan 2024). Influence crawling via sitemaps, server responsiveness, and robots controls.
- Google's canonical crawling/robots reference moved to **developers.google.com/crawling** (migrated 2025-11-20); IP-range files relocated to `/crawling/ipranges/` and `googlebot.json` was renamed `common-crawlers.json`.

#### AI Crawler Management

As of 2025-2026, AI companies actively crawl the web to train models and power AI search. Managing these crawlers via robots.txt is a critical technical SEO consideration.

**Known AI crawlers:**

| Crawler | Company | robots.txt token | Purpose |
|---------|---------|-----------------|---------|
| GPTBot | OpenAI | `GPTBot` | Model training |
| ChatGPT-User | OpenAI | `ChatGPT-User` | Real-time browsing |
| ClaudeBot | Anthropic | `ClaudeBot` | Model training |
| PerplexityBot | Perplexity | `PerplexityBot` | Search index + training |
| Bytespider | ByteDance | `Bytespider` | Model training |
| Google-Extended | Google | `Google-Extended` | Gemini training (NOT search) |
| CCBot | Common Crawl | `CCBot` | Open dataset |

**Key distinctions:**
- Blocking `Google-Extended` prevents Gemini training use but does NOT affect Google Search indexing or AI Overviews (those use `Googlebot`)
- Blocking `GPTBot` prevents OpenAI training but does NOT prevent ChatGPT from citing your content via browsing (`ChatGPT-User`)
- ~3-5% of websites now use AI-specific robots.txt rules

**Example, selective AI crawler blocking:**
```
# Allow search indexing, block AI training crawlers
User-agent: GPTBot
Disallow: /

User-agent: Google-Extended
Disallow: /

User-agent: Bytespider
Disallow: /

# Allow all other crawlers (including Googlebot for search)
User-agent: *
Allow: /
```

**Recommendation:** Consider your AI visibility strategy before blocking. Being cited by AI systems drives brand awareness and referral traffic. Cross-reference the `seo-geo` skill for the full AI crawler/fetcher taxonomy.

> **User-triggered fetchers ignore robots.txt by design.** Google now documents **Google-Agent** (Project Mariner, agentic browsing) plus **Google-NotebookLM** and **Google Messages** as *user-triggered* fetchers that **cannot be blocked via robots.txt**. Use server-side access controls instead. By contrast, `Google-Extended` and `Google-CloudVertexBot` obey robots.txt. Emerging: **Web Bot Auth** (RFC 9421) lets bots authenticate cryptographically via a `Signature-Agent` header + key directory at `agent.bot.goog` (used by Google-Agent); reverse-DNS verification remains the fallback.

### 2. Indexability
- Canonical tags: self-referencing, no conflicts with noindex
- Duplicate content: near-duplicates, parameter URLs, www vs non-www
- Thin content: pages below minimum word counts per type
- Pagination: rel=next/prev or load-more pattern
- Hreflang: correct for multi-language/multi-region sites
- Index bloat: unnecessary pages consuming crawl budget

### 3. Security
- HTTPS: enforced, valid SSL certificate, no mixed content
- Security headers:
  - Content-Security-Policy (CSP)
  - Strict-Transport-Security (HSTS)
  - X-Frame-Options
  - X-Content-Type-Options
  - Referrer-Policy
- HSTS preload: check preload list inclusion for high-security sites
- **Back-button hijacking** (spam-policy violation, malicious practices): flag pages that defeat the Back button via `history.pushState`/`replaceState` (including scripts injected by third-party ad/library platforms). Added to Google's spam policies 2026-04-13; **enforcement live since 2026-06-15** (manual actions + automated demotions): treat as Critical.

### 4. URL Structure
- Clean URLs: descriptive, hyphenated, no query parameters for content
- Hierarchy: logical folder structure reflecting site architecture
- Redirects: no chains (max 1 hop), 301 for permanent moves
- URL length: flag >100 characters
- Trailing slashes: consistent usage

### 5. Mobile Optimization & Page Experience
- Responsive design: viewport meta tag, responsive CSS
- Touch targets: minimum 48x48px with 8px spacing
- Font size: minimum 16px base
- No horizontal scroll
- Mobile-first indexing: Googlebot Smartphone is the primary crawler (rollout completed 2024). A mobile version is **not strictly required** (Google says "very strongly recommended"), sites that don't work on mobile can still be indexed, but the real risk is **content/parity loss**, not hard exclusion.
- **Mobile/desktop content parity** (highest-value mobile check): equivalent primary content, matching robots meta tags, matching titles/descriptions, equivalent structured data, crawlable resources; avoid lazy-loading primary content that requires user interaction.
- **Intrusive interstitials / ad density**: flag full-page interstitials, standalone consent-redirect pages, persistent blocking dialogs, and excessive/distracting ad density (a named page-experience aspect). Acceptable: small banners, standard CMS/legal dialogs.
- **"Read more" deep links**: keep key content **immediately visible on load** (not behind tabs/accordions), don't hijack scroll on load, and preserve URL hash fragments, content hidden behind expandable sections is less likely to qualify.

> **Page experience is guidance, not a single ranking system.** Only **Core Web Vitals** feeds ranking directly; **HTTPS** is a confirmed but lightweight signal (affects <~1% of queries). Relevance can still win even when page experience is sub-par, so don't over-weight security headers. Note: the standalone **Page Experience report was removed** from Search Console (monitor via the Core Web Vitals + HTTPS reports).

### 6. Core Web Vitals
- **LCP** (Largest Contentful Paint): target <=2.5s
- **INP** (Interaction to Next Paint): target <=200ms
  - INP replaced FID on March 12, 2024. FID was removed from Chrome's field-data tools (CrUX API, PageSpeed Insights) on September 9, 2024 (Lighthouse is a lab tool that never reported FID). Do NOT reference FID anywhere.
- **CLS** (Cumulative Layout Shift): target <=0.1
- Evaluation uses 75th percentile of real user data
- Use PageSpeed Insights API or CrUX data if MCP available

### 7. Structured Data
- Detection: JSON-LD (preferred), Microdata, RDFa
- Validation against Google's supported types
- See seo-schema skill for full analysis

### 8. JavaScript Rendering
- Check if content visible in initial HTML vs requires JS
- Identify client-side rendered (CSR) vs server-side rendered (SSR)
- Flag SPA frameworks (React, Vue, Angular) that may cause indexing issues
- Verify dynamic rendering setup if applicable

#### JavaScript SEO: Canonical & Indexing Guidance (December 2025)

Google updated its JavaScript SEO documentation in December 2025 with critical clarifications:

1. **Canonical conflicts:** If a canonical tag in raw HTML differs from one injected by JavaScript, Google may use EITHER one. Ensure canonical tags are identical between server-rendered HTML and JS-rendered output.
2. **noindex with JavaScript:** If raw HTML contains `<meta name="robots" content="noindex">` but JavaScript removes it, Google MAY still honor the noindex from raw HTML. Serve correct robots directives in the initial HTML response.
3. **Non-200 status codes:** Google does NOT render JavaScript on pages returning non-200 HTTP status codes. Any content or meta tags injected via JS on error pages will be invisible to Googlebot.
4. **Structured data in JavaScript:** Product, Article, and other structured data injected via JS may face delayed processing. For time-sensitive structured data (especially e-commerce Product markup), include it in the initial server-rendered HTML.

**Best practice:** Serve critical SEO elements (canonical, meta robots, structured data, title, meta description) in the initial server-rendered HTML rather than relying on JavaScript injection.

### 9. IndexNow Protocol
- Check if site supports IndexNow for Bing, Yandex, Naver
- Supported by search engines other than Google
- Recommend implementation for faster indexing on non-Google engines

## Agent-Friendly Pages & Agentic Browsing

AI agents (not just AI summarizers) increasingly read sites through three
channels: vision models on screenshots, raw HTML/DOM, and the **accessibility
tree** (the cleanest signal). Audit criteria: semantic HTML (real `<button>`
and `<a>`, not `<div onclick>`), label associations, interactive target sizing,
layout stability across templates, `cursor: pointer` correctness, live in
`references/agent-friendly-pages.md`.

Google now ships a Lighthouse **Agentic Browsing** category (default-on since
Lighthouse 13.3.0, Chrome 150+; buckets: agent-centric accessibility, CLS +
llms.txt, three WebMCP audits). It reports a **fractional pass-ratio (X of N),
not a 0-100 score**, keep that distinct from this skill's own Agent-UX 0-100
heuristic below. The PSI REST API does not expose it; run via Lighthouse CLI
`--only-categories=agentic-browsing`, DevTools, or the PSI web UI. See
`references/agent-friendly-pages.md`.

### Audit command

```bash
# Render with Playwright + capture accessibility tree, then score
claude-seo run agent_ux_check.py https://example.com --json
```

The scanner outputs an Agent-UX score (0-100) plus itemized issues:
- HTML findings: real buttons / anchors, `<div onclick>` widgets, semantic
  landmarks, inputs without `<label for>`, inputs without ARIA labels
- Accessibility tree findings: total nodes, interactive nodes, unnamed
  interactive elements, `role="generic"` ratio

The accessibility-tree snapshot uses Playwright's
`page.accessibility.snapshot(interesting_only=False)`. To capture the tree
without scoring, use `claude-seo run render_page.py <url> --a11y-tree --json`.

Surface findings as **opportunities**, not failures; don't gate audits on a
sub-100 Agent-UX score. WebMCP origin-trial/sign-up status needs verification,
and absence of WebMCP support is still an opportunity, not a defect.

## Output

### Technical Score: XX/100

### Category Breakdown
| Category | Status | Score |
|----------|--------|-------|
| Crawlability | pass/warn/fail | XX/100 |
| Indexability | pass/warn/fail | XX/100 |
| Security | pass/warn/fail | XX/100 |
| URL Structure | pass/warn/fail | XX/100 |
| Mobile | pass/warn/fail | XX/100 |
| Core Web Vitals | pass/warn/fail | XX/100 |
| Structured Data | pass/warn/fail | XX/100 |
| JS Rendering | pass/warn/fail | XX/100 |
| IndexNow | pass/warn/fail | XX/100 |

### Critical Issues (fix immediately)
### High Priority (fix within 1 week)
### Medium Priority (fix within 1 month)
### Low Priority (backlog)

## DataForSEO Integration (Optional)

If DataForSEO MCP tools are available, use `on_page_instant_pages` for real page analysis (status codes, page timing, broken links, on-page checks), `on_page_lighthouse` for Lighthouse audits (performance, accessibility, SEO scores), and `domain_analytics_technologies_domain_technologies` for technology stack detection.

## Google API Integration (Optional)

If Google API credentials are configured, use `claude-seo run pagespeed_check.py <url> --json` for real PSI + CrUX field data (replaces lab-only CWV estimates), `claude-seo run crux_history.py <url> --json` for 25-week CWV trends, and `claude-seo run gsc_inspect.py <url> --json` for real indexation status per URL.

## Error Handling

| Scenario | Action |
|----------|--------|
| URL unreachable | Report connection error with status code. Suggest verifying URL, checking DNS resolution, and confirming the site is publicly accessible. |
| robots.txt not found | Note that no robots.txt was detected at the root domain. Recommend creating one with appropriate directives. Continue audit on remaining categories. |
| HTTPS not configured | Flag as a critical issue. Report whether HTTP is served without redirect, mixed content exists, or SSL certificate is missing/expired. |
| Core Web Vitals data unavailable | Note that CrUX data is not available (common for low-traffic sites). Suggest using Lighthouse lab data as a proxy and recommend increasing traffic before re-testing. |