What Is AGENTS.md?

What it is: An open Markdown file standard that AI coding agents read at the start of every session to learn a project’s rules, conventions, and commands. Stewarded by the Agentic AI Foundation under the Linux Foundation; supported natively by Codex, Cursor, GitHub Copilot, Gemini CLI, and most major agents.
Who it is for: Anyone using AI coding agents on a real codebase. AGENTS.md is the cheapest reliability upgrade you can make.
Best if: You want a quick definition of the file and how it fits with CLAUDE.md and README.md.
Skip if: You want the full walkthrough — read our complete AGENTS.md guide instead. Want one practical AI workflow every morning? Subscribe to our free daily newsletter.

Table of Contents

AGENTS.md is a plain Markdown file you place at the root of a code project. AI coding agents like Codex, Cursor, and GitHub Copilot read it automatically at the start of every session and use it as a project-specific instruction file. The official spec at agents.md describes it as “a README for agents.”

The format emerged in 2025 from a collaboration between OpenAI Codex, Amp (Sourcegraph), Jules (Google), Cursor, and Factory. It is now stewarded by the Agentic AI Foundation under the Linux Foundation. Over 60,000 open-source projects use AGENTS.md as of 2026, including OpenAI’s own main repository (which contains 88 nested AGENTS.md files).

Why does AGENTS.md matter?

Before AGENTS.md, every AI coding tool had its own special config file. Anthropic used CLAUDE.md, Cursor used .cursorrules, others had their own. Teams maintained three or four parallel files. The industry converging on one open standard means you write the file once and every supported tool reads it.

The reliability benefit is the bigger story. AI coding agents fail most often because they don’t know your project’s conventions, run commands, or no-go zones — problems an AGENTS.md fixes in 30 minutes of one-time work. The Thoughtworks Technology Radar (Volume 34, April 2026) placed AGENTS.md at “Trial,” signalling enterprise readiness.

What does AGENTS.md typically contain?

Working AGENTS.md files in 2026 converge on eight common sections:

Project overview — one paragraph on what the codebase does
Setup commands — exact install / configuration steps
Run commands — how to start the dev server, worker, or CLI
Test commands — including a fast smoke test for verification
Code style and conventions — linter, formatter, import rules
Folder map — where the main parts of the codebase live
Do not touch — generated files, vendored code, legacy modules
Commit and PR conventions — how the team works

None are required. Keep the first version under 2 KB — agents lose signal in long files.

How does AGENTS.md compare to CLAUDE.md and README.md?

README.md is for human readers (project overview, install, license).
AGENTS.md is for AI agents (operational density — every command, every convention, every gotcha).
CLAUDE.md is the Anthropic-specific equivalent of AGENTS.md. Claude Code reads CLAUDE.md natively but does NOT yet read AGENTS.md as of May 2026. The community workaround is a symlink: ln -s AGENTS.md CLAUDE.md.

Related terms

Learn more on Beginners in AI

What is AGENTS.md? A Beginner’s Guide (full walkthrough)
Why AI Coding Agents Fail
CLAUDE.md: The File That Makes Claude Code Smarter
Claude Code Beginners Guide
AI Glossary

Sources and further reading

Last reviewed: May 2026. AI terminology evolves quickly — verify specifics on the official source pages above.

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What Is AGENTS.md? — AI Glossary

What is AGENTS.md?