Claude Code 2.1.277 now reads AGENTS.md across 60k+ repos
Claude Code was the last major AI coding tool that wouldn’t read an AGENTS.md file. As of version 2.1.277, shipped September 18, that gap is closed.
What Changed
Anthropic added a fallback rule: if Claude Code doesn’t find a CLAUDE.md file (or any of its recognized variants) in the project hierarchy, it now reads AGENTS.md instead. Users can also configure their setups to prioritize one format over the other, or run both simultaneously.
Before this, developers juggling Claude Code alongside OpenAI Codex, GitHub Copilot, or Gemini CLI had to maintain separate instruction files per tool, or wire up symlinks and one-line imports to point Claude Code at an AGENTS.md file. Those workarounds broke in CI/CD pipelines and confused new team members who didn’t know why a nearly empty file was importing instructions from somewhere else in the repo.
Why AGENTS.md Matters
AGENTS.md is a tool-agnostic Markdown file that tells AI coding agents how to behave inside a project. The format has spread fast: over 60,000 repositories now include one. OpenAI Codex reads it. GitHub Copilot reads it. Gemini CLI reads it. Claude Code was the notable holdout until now.
Native fallback support means a single AGENTS.md file can now serve as the baseline instruction set across every major AI coding agent on the market. Teams that want Claude-specific behavior on top can still layer a CLAUDE.md file, but the baseline works without any tool-specific setup.
One Caveat
The AGENTS.md fallback is not available on Bedrock, Vertex, or Foundry. Developers on those platforms still need to use the CLAUDE.md format for now.
The update shipped one day after Anthropic announced a redesign of Claude Code Projects focused on coordinating multi-agent threads, on September 17.
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