I have bad news for you: LLMs are not reading llms.txt nor AGENTS.md files from servers. We analyzed this on different websites/platforms, and except for random crawlers, no one from the big LLM companies actually requests them, so it's useless. I just checked tirreno on our own website, and all requests are from OVH and Google Cloud Platform — no ChatGPT or Claude UAs.
I see Bun (which was bought by Anthropic) has all its documentation in llms.txt[0]. They should know if Claude uses it or wouldn't waste the effort in building this.