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:

• Site URL: Base domain (e.g., https://example.com )

• Indexing scope: Full site, partial, or specific paths to exclude

• 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