llms.txt file for LLM guidanceWhat it checks and how to fix it

What it checks

Fetches /llms.txt and /llms-full.txt from the site and checks that they answer 200 with a non-empty body. When the project allows AI crawlers, it passes if either file is published and warns if neither is; when the project blocks AI crawlers, it is the other way round. If a file could not be fetched at all, the result is inconclusive instead of a verdict.

Why it matters

llms.txt is a short Markdown file at the root of a site that tells AI assistants what the site is about and which pages matter, in a form they can read without parsing navigation, scripts and cookie banners. It makes it more likely that ChatGPT, Claude or Perplexity describe your product correctly and link to the right page. It costs one file and no maintenance beyond keeping the links current.

How to fix it

Publish a Markdown file at https://example.com/llms.txt, served as text/plain or text/markdown:

# Example Inc

> Example Inc makes invoicing software for freelancers: quotes, invoices, payment reminders and tax reports.

## Product

- [Features](https://example.com/features): What the product does.
- [Pricing](https://example.com/pricing): Plans and prices.

## Docs

- [Getting started](https://example.com/docs/start): Create an account and send your first invoice.
- [API reference](https://example.com/docs/api): REST API for invoices and clients.

Start with an H1 with the name, a one-paragraph summary in a blockquote, then sections of links with a short description each. Optionally publish /llms-full.txt with the full text of your key pages.

In Rails, put the file in public/llms.txt; on a static host, at the root of the build output. Check that no redirect or login wall sits in front of it.