llms txt

/llms.txt is a proposal by Jeremy Howard of Answer.AI (published 3 September 2024; v2 modified 10 August 2026) for a markdown file at a site root or path that points agents to LLM-friendly markdown versions of key pages; v2 adds discovery through rel="describedby" and rel="alternate" type="text/markdown" links or Link headers. Google Search does not use it: since June 2026 Google's AI optimization guide says Search does not use such machine-readable or AI text files and that they neither help nor hurt visibility. John Mueller had compared llms.txt to the keywords meta tag in April 2025. Its documented uses are agentic. Chrome Lighthouse's experimental Agentic Browsing category checks /llms.txt, where a 404 counts as not applicable and only a server error fails. The AI labs and documentation platforms publish it for developer docs. We located no answer engine that documents using it for retrieval or ranking.