September 19, 2026
One instruction file for every agent: Claude Code reads AGENTS.md from version 2.1.277
In version 2.1.277, Claude Code picks up AGENTS.md automatically if the folder has no CLAUDE.md.
Gergely Orosz
@gergelyorosz
Want an example of how the very best model and the very best wrapper deliver neither a better nor faster result, but actually slow you down? The Claude Code team took 16 months (!!) longer than OpenCode and Codex to add AGENTS.md support. And 12 longer than Cursor
We're adding support for AGENTS.md to Claude Code. Starting today in version 2.1.277, if there is no CLAUDE.md in a folder, Claude will check for and use AGENTS.md. You can toggle this behavior in /config.
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The “Support AGENTS.md” request sat in the Claude Code repository for nearly a year and collected 6663 reactions.
On 18.09.2026, Anthropic closed it. Projects with agents no longer need to maintain two copies of the same text.
Before and after. Previously, the same rules lived in CLAUDE.md and AGENTS.md, with a symlink or hook keeping them in sync. Now the same AGENTS.md is read by Codex, Cursor, and Claude Code.
How to enable it. Open /config and select Project instructions. The claude-md-and-agents-md setting reads both files, with CLAUDE.md first and AGENTS.md second in every folder. The default is more limited and reads AGENTS.md only where CLAUDE.md is absent both in the working folder and anywhere higher in the tree.
A single CLAUDE.local.md at the top disables AGENTS.md reading entirely, and the same setting fixes it. The old SessionStart hook that printed AGENTS.md into the context should be removed: otherwise, a second copy of the file will enter the context.
OpenAI released the format in August 2025, more than 60 000 open-source projects adopted it, and in December 2025 it moved to the Agentic AI Foundation under the Linux Foundation. Anthropic also contributed MCP there and is a platinum member.
AGENTS.md reading is not yet enabled on Bedrock, Vertex, and Foundry.
