Definition
llms.txt is a proposed standard for a Markdown file at a website's root (/llms.txt) that tells language models what the site is and links its most useful pages with short descriptions.
MegaMCP glossary32 terms
Explained
It was proposed in 2024 (llmstxt.org). Support by the major AI search crawlers is unconfirmed, but coding assistants and agents that read it get a clean map of the site. It's cheap to add and doesn't replace crawlability or good content.
A companion llms-full.txt sometimes contains the full text of key pages.