In Theory There Is No Difference Between Theory and Practice, While In Practice There Is.

In large projects, having a specific AGENTS.md makes the difference between the agent spending half of its context window searching for the right commands, navigating the repo, understanding what is what, etc., and being extremely useful. The larger the repository, the more things it needs to be aware of and the more important the AGENTS.md is. At least that's what I have observed in practice.