Thread

Claude Code reads AGENTS.md only when telemetry is on [fixed]

486 points · 284 comments · pszypowicz

mpoteat · 1790168190 · focus · HN ↗
Sorry folks, this is a rollout artifact, we needed a way to turn this off remotely via feature flags if it broke something, and with telemetry off you don't get those. It's already been fixed as part of v2.1.281 releasing today.
The mod is source available here: <a href="https://github.com/anthropics/claude-code/tree/main/mods/agents-md" rel="nofollow">https://github.com/anthropics/claude-code/tree/main/mods/age...
Apologies again folks, this was a fully human error on my part - I should've found a better way to launch with a kill-switch.
1. mpoteat · 1790168466 · focus · HN ↗
  The AGENTS.md support was implemented via our new extensibility system for CC, called Mods, which is launching soon-ish. A mod is a plugin with a new type of hook, which we call a function hook.
  If folks play around with it, I would love feedback on the relevant issue: <a href="https://github.com/anthropics/claude-code/issues/91870" rel="nofollow">https://github.com/anthropics/claude-code/issues/91870
  Mods allow quite a bit more customizability and control. I really believe in the idea.
  1. rickette · 1790168940 · focus · HN ↗
    The only difference between CLAUDE.md and AGENTS.md is the filename. Do you really need a whole plugin system to support that use case? Feels like this could have been a one line change.
    pdpi · 1790170985 · focus · HN ↗
    The plugin system itself was probably already in the making, and they just chose to implement this tiny feature as a plugin to try it out.
    As for the only difference being the file name, that's an untested assumption. Up until now, Claude hadn't supported AGENTS.md, and it's a simple application of Hyrum's Law that somebody, somewhere, was taking advantage of that to give one set of instructions to Claude, and a different set of instructions to some other provider. The correct behaviour in the presence of both files is not obvious, either.
    Having a kill switch for the change is a perfectly reasonable safety measure in case something goes horribly wrong.
    Wowfunhappy · 1790173191 · focus · HN ↗
    > somebody, somewhere, was taking advantage of that to give one set of instructions to Claude, and a different set of instructions to some other provider.
    I'm this person, I am actively doing this! I have some instructions which the Claude models need and OpenAI models will do by themselves. If the OpenAI models see the Claude instructions, they will go way overboard in a way I don't want.
    Mind, the change does not affect me at all, because when both instructions are present Claude continues to read CLAUDE.md and Codex continues to read AGENTS.md. But if Claude started preferring AGENTS.md, that would be mildly annoying.
    californical · 1790175580 · focus · HN ↗
    Within agents.md, an idea. Feel free to steal if you work on this:
    Model.Claude*: Do this one thing Model.Claude.Opus.4.8: Extra specific instructions Model.*: This is relevant to everyone Harness.ClaudeCode*: Why not, let’s allow harness specific instructions so you can do things differently depending how you’re working
    dotancohen · 1790176554 · focus · HN ↗
    I would like to subscribe to your newsletter.
    Seriously, though, this is a great idea. Good communicators know to tailor their discourse to their audience. LLMs are just as sensitive to small variations in prompts, and just as inconsistent between them, as are humans.
    Wowfunhappy · 1790177254 · focus · HN ↗
    It's not a bad idea, although at that point it probably shouldn't be a .md file anymore. You'd want to use YAML or something.
    markhahn · 1790178739 · focus · HN ↗
    careful, that might lead to programming. using, you know, a programming language.
    californical · 1790181050 · focus · HN ↗
    Sorry how about this:
    # Models.Claude\*:
    Maybe now it can be in a .md again :D
    everforward · 1790177907 · focus · HN ↗
    I did this at one point with Jinja templates.
    I wrote an agent launcher sort of bash script. Pass in the command to start the agent, the script checks if there’s a Jinja file in a special directory matching that name, and builds it to AGENTS.md. Then it launches the agent.
    I was trying to use it as a sort of janky RAG. I had a bunch of snippets (one for DB architecture, one for how load balancing works, etc), and my Jinja files were mostly a list of snippets to pull in. Voila, a bunch of agents that share little pieces of info but have a single source of truth.
    I never got a ton of value tbh, it was very good at just grepping the snippets.

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