Why it matters
The honest take is itself the differentiator: most write-ups oversell llms.txt. It costs almost nothing to ship and may help discovery, but no major engine has confirmed it as a signal — so do it, and don’t expect miracles.
In practice
Anthropic publishes a live llms.txt for its developer docs at platform.claude.com/docs/llms.txt — a Markdown index of its API and guide pages with short descriptions, so an LLM can pull the right reference without scraping the whole HTML site. An industrial distributor could do the same: a /llms.txt pointing assistants to its hydraulic-fitting cross-reference and spec pages. The catch — Google's Gary Illyes said in July 2025 that Google won't use llms.txt, so treat it as cheap hygiene, not a ranking lever.
Source: platform.claude.com