You'd put the things that aren't up to personal preference in there, like an AI disclosure / contribution policy or what changes should look like to be reviewable. You usually don't need to tell humans "don't change things for the sake of changing them" because we don't like to do more work than we have to, but agents do.

You can also include a compact "table of contents," describing what lives where in the project. It saves at most a little bit of exploration though so I don't know if it's really worth the maintenance

For agents (semi-autonomous) I think it's more similar to introductory developer docs. Which are usually committed.

Like formatters and git ignore configuration, some agent instructions are personal and those should not be commited. But some are worth sharing. Having formatter config in a repo is not uncommon. And in this case the file is only a link to the readme, so the agent reads the contrib guidelines.

A contributor still has global config for their personal preferences. It makes sense to me, anyway. My biggest issue is it's not deterministic. Someone else could have a version that works better or uses fewer tokens for the same thing.

At work we commit the whole .claude folder, though we carve out some space for personal agents and skills.

To quote the research paper conclusion...

Conclusion We evaluate the impact of context files on coding agent performance for four common coding agents on SWE-BENCH and the novel CTXBENCH, built from recent GitHub issues and less popular repositories containing developer-written context files. We find that all context files consistently increase the cost and number of steps required to complete tasks. LLM-generated context files have a marginal negative effect on task success rates, while developer-written ones provide a marginal performance gain, neither statistically significant. Our trace analyses show that instructions in context files are generally followed and lead to more test- ing and broader exploration; however, they do not function as effective repository overviews. Over- all, our results suggest that context files don’t improve coding agent performance, and should only contain specific additional instructions beyond what is already available in the codebase. This high- lights a concrete gap between current agent-developer recommendations and observed outcomes, and motivates future work on principled ways to automatically generate concise, task-relevant guid- ance for coding agents.

That sounds like "Agents.MD doesn't work" to me.

Am I missing something?

BSD is too usable. will have AI in it before long.

No, that’s an unrealistic reactionary view which fails to address the gains that can be had, has no way to be enforced, and is a short sighted take.