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AGENTS.md

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This page is about the AGENTS.md file format. For site-level LLM indexes, see llms.txt; for packaged agent skills, see Agent Skills.

Overview

AGENTS.md is a simple, open format for guiding coding agents: a Markdown file that gives AI coding agents a dedicated, predictable place for the context and instructions they need to work on a project [1]. It complements a README by holding the extra context agents need, such as build steps, tests and conventions that might clutter a README or are not relevant to human contributors [1]. There are no required fields: it is standard Markdown, with any headings the author likes [1].

The file goes at the root of the repository, and a large monorepo can place another AGENTS.md inside each package; the closest AGENTS.md to the edited file wins, and explicit user chat prompts override everything [1]. OpenAI's Codex launch post of 16 May 2025 already said Codex can be guided by AGENTS.md files in a repository [3]; the format itself emerged from work across OpenAI Codex, Amp, Jules from Google, Cursor and Factory, and was released by OpenAI in August 2025 [1][2]. On 9 December 2025 the Linux Foundation announced the Agentic AI Foundation (AAIF) with AGENTS.md as one of three founding projects, alongside MCP and goose, and said it had been adopted by more than 60,000 open source projects and agent frameworks [2]. The project says AGENTS.md is now stewarded by the AAIF under the Linux Foundation [1].

Who uses it

Who reads it

Recent coverage

See also

References

  1. AGENTS.md project (agentsmd/agents.md), AGENTS.md, undated site; checked 2026-10-28: "A simple, open format for guiding coding agents, used by over 60k open-source projects." "Think of AGENTS.md as a README for agents: a dedicated, predictable place to provide the context and instructions to help AI coding agents work on your project." "AGENTS.md complements this by containing the extra, sometimes detailed context coding agents need: build steps, tests, and conventions that might clutter a README or aren't relevant to human contributors." "Are there required fields? No. AGENTS.md is just standard Markdown. Use any headings you like; the agent simply parses the text you provide." "Create an AGENTS.md file at the root of the repository." "Place another AGENTS.md inside each package. Agents automatically read the nearest file in the directory tree, so the closest one takes precedence and every subproject can ship tailored instructions." "The closest AGENTS.md to the edited file wins; explicit user chat prompts override everything." "AGENTS.md emerged from collaborative efforts across the AI software development ecosystem, including OpenAI Codex, Amp, Jules from Google, Cursor, and Factory." "AGENTS.md is now stewarded by the Agentic AI Foundation under the Linux Foundation." — https://agents.md/
  2. The Linux Foundation, Linux Foundation Announces the Formation of the Agentic AI Foundation (AAIF), Anchored by New Project Contributions Including Model Context Protocol (MCP), goose and AGENTS.md, 2025-12-09: "The Linux Foundation, the nonprofit organization enabling mass innovation through open source, today announced the formation of the Agentic AI Foundation (AAIF), and founding contributions of three leading projects driving innovation in open source AI; Anthropic's Model Context Protocol (MCP), Block's goose, and OpenAI's AGENTS.md." "Released by OpenAI in August 2025, AGENTS.md is a simple, universal standard that gives AI coding agents a consistent source of project-specific guidance needed to operate reliably across different repositories and toolchains." "AGENTS.md has already been adopted by more than 60,000 open source projects and agent frameworks including Amp, Codex, Cursor, Devin, Factory, Gemini CLI, GitHub Copilot, Jules and VS Code among others." — https://www.linuxfoundation.org/press/linux-foundation-announces-the-formation-of-the-agentic-ai-foundation
  3. OpenAI, Introducing Codex, 2025-05-16 (live page returns 403 to automated fetches; Internet Archive copy of 2026-10-22): "Codex can be guided by AGENTS.md files placed within your repository." — https://web.archive.org/web/20261022165127/https://openai.com/index/introducing-codex/
  4. OpenAI, Custom instructions with AGENTS.md (Codex docs), no date shown: "Codex reads AGENTS.md files before doing any work." — https://learn.chatgpt.com/docs/agent-configuration/agents-md
  5. GitHub, Adding repository custom instructions for GitHub Copilot (GitHub Docs), no date shown: "You can create one or more AGENTS.md files, stored anywhere within the repository. When Copilot is working, the nearest AGENTS.md file in the directory tree will take precedence." — https://docs.github.com/en/copilot/how-tos/copilot-on-github/customize-copilot/add-custom-instructions/add-repository-instructions
  6. Microsoft, Visual Studio Code August 2025 (version 1.104) release notes, 2025-09-11: "An AGENTS.md file lets you provide context and instructions to the agent. Starting from this release, when you have an AGENTS.md file in your workspace root(s), it is automatically picked up as context for chat requests." — https://code.visualstudio.com/updates/v1_104
  7. Cursor, Rules (Cursor Docs), no date shown: "Cursor supports AGENTS.md in the project root and subdirectories." — https://cursor.com/docs/rules
  8. Anthropic, How Claude remembers your project (Claude Code Docs), no date shown: "Claude Code can read AGENTS.md as your project instructions, so a repository already set up for other coding agents works without adding a CLAUDE.md, an import, or a setting." "Reading AGENTS.md directly requires Claude Code v2.1.277 or later." "By default, Claude reads AGENTS.md only when you have no CLAUDE.md in your working directory or above it." — https://code.claude.com/docs/en/memory
  9. Google, Jules Agent Update: Faster, Smarter, More Reliable (Jules changelog), 2025-06-20: "Smarter context. Jules reads from AGENTS.md if it's in your repo." — https://jules.google/docs/changelog/2025-06-20/
  10. Amp, From AGENT.md to AGENTS.md (Amp news), 2025-08-20: "True to our word, and as of today, Amp will look for AGENTS.md files (while staying backwards compatible with existing AGENT.md files, of course)" — https://ampcode.com/news/AGENTS.md
  11. Cognition, AGENTS.md files for Devin (Devin Docs), no date shown: "Devin supports AGENTS.md - a simple, open standard for providing context and instructions to AI agents." — https://docs.devin.ai/onboard-devin/agents-md
  12. Factory, AGENTS.md (Factory Documentation), no date shown: "AGENTS.md gives Droid the project briefing it should carry into every session: how to install, run, test, edit, verify, and stay inside your repository's boundaries." — https://docs.factory.com/harness/agents-md
  13. Stride, What 7,370 popular GitHub repositories put in AGENTS.md and CLAUDE.md, 2026-09-27: "Of the 7,370 active public repositories on GitHub with 5,000 or more stars, 1,864 (25.3%) had an AGENTS.md at the root on 27 September 2026, and 33.4% had at least one instruction file for coding agents." — https://www.stride.page/research/agents-md-claude-md-study-2026
  14. Zarzycki, P., What Open-Source Projects Tell Their Coding Agents: A Census of AGENTS.md and CLAUDE.md (arXiv:2610.31715), submitted 2026-10-22, revised 2026-10-26: "Of the 22,854 repositories, 6,006 (26.3%) have a root AGENTS.md, a root CLAUDE.md, or both." "2,566 adopters have only AGENTS.md, 1,052 only CLAUDE.md, and 2,388 both." — https://arxiv.org/html/2610.31715
  15. Galster, M., Mohsenimofidi, S., Lulla, J. L., Abubakar, M. A., Treude, C. and Baltes, S., Harness Engineering for Agentic AI Coding Tools: An Exploratory Study (arXiv:2602.14690v5; based on their AIware 2026 paper), submitted 2026-02-16, v5 revised 2026-06-30: "An additional 493 repositories (17.3%) used AGENTS.md as a tool-agnostic standard without any tool-specific configuration artifact; these are shown separately in the analysis (see Table 2, footnote d)." "Our results show convergence on AGENTS.md as a tool-agnostic configuration file." — https://arxiv.org/html/2602.14690v5

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