SEO Technical: robots.txt

Guides configuration and auditing of robots.txt for search engine and AI crawler control.

When invoking: On first use, if helpful, open with 1–2 sentences on what this skill covers and why it matters, then provide the main output. On subsequent use or when the user asks to skip, go directly to the main output.

Scope (Technical SEO)

• Robots.txt: Configure Disallow/Allow, Sitemap, Clean-param; audit for accidental blocks
• Crawler access: Path-level crawl control; AI crawler allow/block strategy
• Differentiation: robots.txt = crawl control (who accesses what paths); noindex = index control (what gets indexed). See indexing for page-level exclusions.

Initial Assessment

Check for project context first: If .claude/project-context.md or .cursor/project-context.md exists, read it for site URL and indexing goals.

Identify:

1. Site URL: Base domain (e.g., https://example.com)
2. Indexing scope: Full site, partial, or specific paths to exclude
3. AI crawler strategy: Allow search/indexing vs. block training data crawlers

Best Practices

Purpose and Limitations

Point	Note
Purpose	Controls crawler access; does NOT prevent indexing (disallowed URLs may still appear in search without snippet)
Advisory	Rules are advisory; malicious crawlers may ignore
Public	robots.txt is publicly readable; use noindex or auth for sensitive content. See indexing

Crawl vs Index vs Link Equity (Quick Reference)

Tool	Controls	Prevents indexing?
robots.txt	Crawl (path-level)	No—blocked URLs may still appear in SERP
noindex (meta / X-Robots-Tag)	Index (page-level)	Yes. See indexing
nofollow	Link equity only	No—does not control indexing

When to Use robots.txt vs noindex

Use	Tool	Example
Path-level (whole directory)	robots.txt	Disallow: /admin/, Disallow: /api/, Disallow: /staging/
Page-level (specific pages)	noindex meta / X-Robots-Tag	Login, signup, thank-you, 404, legal. See indexing for full list
Critical	Do NOT block in robots.txt	Pages that use noindex—crawlers must access the page to read the directive

Paths to block in robots.txt: /admin/, /api/, /staging/, temp files. Paths to use noindex (allow crawl): /login/, /signup/, /thank-you/, etc.—see indexing.

Location and Format

Item	Requirement
Path	Site root: https://example.com/robots.txt
Encoding	UTF-8 plain text
Standard	RFC 9309 (Robots Exclusion Protocol)

Core Directives

Directive	Purpose	Example
User-agent:	Target crawler	User-agent: Googlebot, User-agent: *
Disallow:	Block path prefix	Disallow: /admin/
Allow:	Allow path (can override Disallow)	Allow: /public/
Sitemap:	Declare sitemap absolute URL	Sitemap: https://example.com/sitemap.xml
Clean-param:	Strip query params (Yandex)	See below

Critical: Do Not Block

Do not block	Reason
CSS, JS, images	Google needs them to render pages; blocking breaks indexing
/_next/ (Next.js)	Breaks CSS/JS loading; static assets in GSC "Crawled - not indexed" is expected. See indexing
Pages that use noindex	Crawlers must access the page to read the noindex directive; blocking in robots.txt prevents that

Only block: paths that don't need crawling: /admin/, /api/, /staging/, temp files.

AI Crawler Strategy

robots.txt is effective for all measured AI crawlers (Vercel/MERJ study, 2024). Set rules per user-agent; check each vendor's docs for current tokens.

User-agent	Purpose	Typical
OAI-SearchBot	ChatGPT search	Allow
GPTBot	OpenAI training	Disallow
Claude-SearchBot	Claude search	Allow
ClaudeBot	Anthropic training	Disallow
PerplexityBot	Perplexity search	Allow
Google-Extended	Gemini training	Disallow
CCBot	Common Crawl (LLM training)	Disallow
Bytespider	ByteDance	Disallow
Meta-ExternalAgent	Meta	Disallow
AppleBot	Apple (Siri, Spotlight); renders JS	Allow for indexing

Allow vs Disallow: Allow search/indexing bots (OAI-SearchBot, Claude-SearchBot, PerplexityBot); Disallow training-only bots (GPTBot, ClaudeBot, CCBot) if you don't want content used for model training. See site-crawlability for AI crawler optimization (SSR, URL management).

Clean-param (Yandex)

Clean-param: utm_source&utm_medium&utm_campaign&utm_term&utm_content&ref&fbclid&gclid

Output Format

• Current state (if auditing)
• Recommended robots.txt (full file)
• Compliance checklist
• References: Google robots.txt

Related Skills

• indexing: Full noindex page-type list; when to use noindex vs robots.txt; GSC indexing diagnosis
• page-metadata: Meta robots (noindex, nofollow) implementation
• xml-sitemap: Sitemap URL to reference in robots.txt
• site-crawlability: Broader crawl and structure guidance; AI crawler optimization
• rendering-strategies: SSR, SSG, CSR; content in initial HTML for crawlers