LLMs.txt Checker + Validator

A usable llms.txt file has an H1 title, a blockquote summary, H2 sections, and absolute http or https links with names. Line numbers in this checklist point at the pasted markdown, which is the same idea as a linter for that format.

A usable file has one H1 on the first content line, a blockquote summary under that title, at least one H2 section, and links written as a markdown list. URLs must be absolute http or https, and the link text cannot be empty. A missing summary is a warning. A missing title, a relative URL, or an empty link name fails.

H1 is one of the values LLMs.txt Checker + Validator puts on screen. The title is one heading on the first content line. A missing title fails. A second H1 is not the shape this file uses.

Read Summary on its own before you mix it with the other rows. The summary is a blockquote under the title. A missing summary warns. It does not by itself fail the file.

Links answers a narrower question than the headline number. Links are a markdown list with absolute URLs. A relative URL or an empty name fails, and the line number is shown. The checker does not request the URL to see if it loads.

Treat Warnings as a label with a specific job. Some issues are warnings. Repeated URLs, a long description, an empty section, and HTML-like text warn. Pass with warnings means the required title and links are present.

The URL box line is worth a full stop. A field for a file address. It is a note only. Paste the markdown. The box is not requested.

A section with no links, a repeated URL, a description longer than 160 characters, and a file that looks like HTML are warnings. The checker does not download the URL box and it does not invent a network score. Paste the file. Line numbers point at that paste.

If you remember one sequence from LLMs.txt Checker + Validator, remember the fields in the order they change a decision. H1 matters because The title is one heading on the first content line. In practice, A missing title fails. The mistake to avoid is this: A second H1 is not the shape this file uses. Summary matters because The summary is a blockquote under the title. In practice, A missing summary warns. The mistake to avoid is this: It does not by itself fail the file. Links matters because Links are a markdown list with absolute URLs. In practice, A relative URL or an empty name fails, and the line number is shown. The mistake to avoid is this: The checker does not request the URL to see if it loads. Warnings matters because Some issues are warnings. In practice, Repeated URLs, a long description, an empty section, and HTML-like text warn. The mistake to avoid is this: Pass with warnings means the required title and links are present. URL box matters because A field for a file address. In practice, It is a note only. The mistake to avoid is this: Paste the markdown. The box is not requested. After that, the checks are simple. The paste is markdown, not a URL. Failures were fixed at the line number. Relative URLs were changed to http or https. A missing summary was treated as a warning. The URL box was left as a note.

The worked example for LLMs.txt Checker + Validator, read as one scene, is this. Paste a file that starts with # Example, a blockquote summary, ## Docs, and a link to https://example.com/guide named Guide. The required rows pass. Leave the summary out and that row warns while the title and link can still pass. Change the guide URL to /guide. The check fails on that line because the URL is relative. The line number is the line in the paste, not a line on a server.

Keep LLMs.txt Checker + Validator as this step only. When the job moves on, the LLMs.txt Generator is the next page: LLMs.txt Generator writes an llms.txt markdown file from a project name, a summary, optional notes, and grouped links. The LLMs.txt Auditor covers a different piece of the same work: LLMs.txt Auditor scores the structure of llms.txt markdown you paste and shows the math behind the score.