Direct answer
The short version.
robots.txt controls crawler access, sitemap.xml lists canonical URLs, security.txt publishes vulnerability-reporting information and llms.txt is an emerging convention for giving language-model tools a concise site guide. They are complementary, not ranking shortcuts.
Key takeaways
Keep these three decisions.
- Give each discovery file one clear job.
- Generate URLs from published content.
- Treat llms.txt as supplementary, not magic markup.
The operating problem
Files are often copied from templates without matching the real site. Important routes are omitted, API paths are exposed to unnecessary crawling, canonical domains stay on localhost and an llms.txt file lists marketing claims that no visible page supports.
A practical system
Generate the sitemap from published routes and stable dates, keep robots rules simple and test the production host. Publish security.txt at the well-known path with a monitored contact and expiry. Use llms.txt as a curated map to human-readable canonical pages, while recognising that major search engines do not require it for AI visibility.
What to measure next
Validate HTTP status, content type, canonical host, crawler access and URL count after every deployment. Monitor crawl and indexing reports, broken links and security-contact delivery. A file is useful only when it stays accurate as the site changes.
Primary and authoritative references
Sources used for context.
Frequently asked questions
Two useful follow-ups.
Does a website need llms.txt to appear in AI search?
No. Google explicitly says special AI text files are not required for its AI search features. llms.txt can still serve as a voluntary site guide for tools that choose to read it.
Where should security.txt be published?
The standard location is /.well-known/security.txt, with a monitored contact, expiry and canonical URL.