How to Create an llms.txt File: An Optional Documentation Index
Create a small llms.txt documentation index with truthful links, versioned context and maintenance checks, without promising SEO or citation gains.
An llms.txt file is an optional, proposed way to give agents a concise guide to a site's information. It is not an indexing command, robots policy or guarantee that any search product will use your pages.
The llms.txt proposal describes a Markdown index with a project name and optional summary/linked sections. Consult the current proposal when implementing it; it can evolve independently of search engines.
Decide whether it solves a real documentation problem
An API documentation site with scattered setup, migration and reference pages may benefit from a curated entry point for its users' agents. A small brochure site with a clear navigation system may have more valuable work to do first.
| Situation | Useful action | Claim to avoid |
|---|---|---|
| Agents struggle to find current API references | Provide an explicit current-docs index | “This improves all AI rankings” |
| Old and new product versions coexist | Label version scope on links and pages | “Every crawler will pick the newest link” |
| The site has crawl/indexing failures | Fix the underlying access issue | “llms.txt replaces a sitemap” |
| No maintenance owner exists | Keep the index minimal or defer it | “A stale file has no cost” |
Google's June 2026 clarification says these files do not affect Google visibility or rankings. Publishing an AI company's own documentation index is also not proof that its search crawler prioritizes every website with one.
A fictional file
# Example Invoice API
> Documentation for developers integrating the Example Invoice API v2.
These pages describe v2. The migration page explains differences from v1.
## Start here
- [Quickstart](https://example.com/docs/quickstart.md): Send a first test invoice.
- [Authentication](https://example.com/docs/auth.md): Configure scoped credentials.
- [Migration](https://example.com/docs/migrate-v2.md): Review breaking changes.
## Reference
- [Invoice fields](https://example.com/docs/invoices.md): Required fields and validation.
The URLs are placeholders. Link only to resources you actually publish. If you offer Markdown versions, ensure they preserve the important qualifications and agree with the human-readable pages.
Publish and verify
- Choose the appropriate location and scope under the current proposal.
- Keep the summary specific: audience, product/version and task.
- Check every linked URL for a public, useful response.
- Ask a consenting test reader or agent to complete one documentation task using the index. Record where navigation failed.
- Assign an owner to update links when docs move or versions change.
That test can establish whether your index helps the tested workflow. It does not measure search ranking or citation lift.
Keep access policies separate
An index link cannot override authentication, a robots directive or noindex. Use the crawler-policy guide for the OpenAI training/search distinction and the technical SEO hub for ordinary indexing diagnosis.
Before announcing “AI-ready” results, state exactly what you shipped: an accessible documentation index with verified links. Use the citation log only for separately observed citation evidence, and do not convert an implementation checklist into a performance claim.