llms.txt: the file AI agents read about you

Agents now browse the web on behalf of people: coding agents fetch docs, assistants research vendors. llms.txt is the convention (llmstxt.org) for giving them a concise, expert-curated overview: an H1 with your name, a blockquote summary, and H2 sections of links to the detail.

Chrome's Lighthouse audits for it. OpenAI, Anthropic and Google publish it for their own docs. If an agent answers a question about your business today, it is probably improvising from your marketing pages — or from someone else's summary of you.

Other tools: SPF · DMARC · llms.txt · Header analyzer