Noesion Radarnoesion.ai
Release2026-09-18

Anthropic added support for OpenAI’s AGENTS.md standard in Claude Code. Starting in version 2.1.277, Claude Code will use AGENTS.md if no CLAUDE.md exists. Users can toggle this behavior with the /config command. The move reduces the need to maintain separate instruction files for different tools. AGENTS.md is a tool-agnostic format for agent instructions. OpenAI contributed AGENTS.md to the Agentic AI Foundation last year. Over 60,000 open source projects already use AGENTS.md. Developers welcomed the change as a step toward better compatibility.

What changed

Claude Code required a CLAUDE.md file for project instructions.

What it unlocks

Using a single AGENTS.md file for both Claude Code and other AI coding tools.

  • 60,000 open source projects using AGENTS.md
  • version 2.1.277

What you need to act on it

  • Claude Code version 2.1.277 or later
  • no CLAUDE.md present in the folder

Sources

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