AGENTS.md in repos

Start here

Drop AGENTS.md in the root of your repository. That is the install. If you take one thing from this project, take this one, because it is free and it is permanent. It is the delivery channel with the least friction by a wide margin: no extension, no API key, no per-request token cost, and nothing for your teammates to configure. They clone the repo and the Standard comes with it.

What picks it up

Most agents that read repository context read it automatically: Codex, Cursor, Copilot's agent mode, and a growing list of others. A standard that lives in one engineer's browser extension is that engineer's preference. A standard that lives in the repo is the project's, and every agent that touches the project is conformant by default.

The Claude Code exception

Claude Code is the exception worth knowing about. It reads CLAUDE.md and ignores AGENTS.md entirely, with no warning and no error. It just runs with no project instructions and you wonder why the output got worse. Don't rename the file, or you fix Claude Code and break everything else. Add a CLAUDE.md alongside AGENTS.md that pulls the real file in. One source of truth, two filenames.

The whole set, or just the one file

/adopt in the VS Code extension writes the whole set for you: AGENTS.md, the CLAUDE.md shim, Copilot instructions, Cursor rules, PSScriptAnalyzerSettings.psd1, and a CI workflow. Or copy the one file by hand and be done in ten seconds. Once those files exist, Copilot, Cursor, and Claude Code follow the Standard with no extension installed at all: cheapest to set up, most durable, zero tokens per call.

The Claude Code shim

A CLAUDE.md holding a single import keeps the Standard in one place:

# CLAUDE.md
# Claude Code reads this file and ignores AGENTS.md.
@AGENTS.md

Symlinks work too: ln -s AGENTS.md CLAUDE.md, if your team is fine with symlinks in git.