agents.md (the spec site)

The home page of the AGENTS.md open format — the first-party source behind the agents-md concept node. AGENTS.md is “a simple, open format for guiding coding agents,” functioning as “a README for agents: a dedicated, predictable place to provide the context and instructions.”

What goes in it

The format is plain Markdown with flexible headings, and suggests (does not require) sections for: project overview, build and test commands, code style, testing instructions, security considerations, commit/PR guidelines, and deployment steps. It explicitly splits roles with the README: the README serves humans (“quick starts, project descriptions, and contribution guidelines”) while AGENTS.md holds the “extra, sometimes detailed context coding agents need” without cluttering human docs.

The nearest-file rule

In monorepos, “agents automatically read the nearest file in the directory tree, so the closest one takes precedence” — each subproject can carry tailored instructions. The scale is concrete: OpenAI’s main repository contains 88 nested AGENTS.md files.

Reach and governance

“Over 60,000 open-source projects” use it (Apache Airflow, Temporal’s Java SDK, OpenAI Codex among them), read by 25+ coding agents including Claude Code, VS Code, Cursor, Zed, Aider, GitHub Copilot, and tools from Google, Cognition, and JetBrains. It is “now stewarded by the Agentic AI Foundation under the Linux Foundation,” having emerged from collaboration across OpenAI, Google, Cursor, Factory, and Amp.

Tier T1 — the standard’s own site. Cited by agents-md.