**Short answer: probably not. It's optional, and it isn't proven to help.**

- **What it is:** llms.txt is a proposed, unofficial standard. Jeremy Howard (fast.ai / Answer.AI) proposed it in September 2024. It's a Markdown file at your site root (`/llms.txt`) that summarizes your site and links to your most useful pages for AI tools.
- **It isn't required:** Unlike robots.txt, no major standard enforces it. Publishing one doesn't guarantee that AI tools will cite or reference your site.
- **Support is inconsistent:** Support varies between AI services. A crawler may fetch the file and still ignore it when it retrieves content. Some SEO vendor articles say it's essential for B2B startups, but those sources have a commercial interest. I didn't find independent evidence of a benefit.
- **When it may be worth it:** It's cheap to add if you have a documentation site, a developer product or a content-heavy site. A short, curated list of your best pages costs little and does no harm.
- **What matters more:** Clear, crawlable pages, good site structure and a sensible robots.txt matter more. Use robots.txt if you want to allow or block AI crawlers.

My search was a single standard query, and most of what came back was low-quality or vendor content. I didn't open any pages. Treat this as a cautious summary, not a definitive one.

SOURCES:
https://miniloop.ai/blog/how-to-build-llms-txt-file-ai-crawlers-2026
https://www.techmagnate.com/?p=58365
https://crawlconsole.com/blog/should-you-add-llms-txt-ai-crawlers
https://gracker.ai/blog/llms-txt-vs-robots-txt
https://www.texta.ai/blog/do-ai-crawlers-read-llms-txt