Claude Code adds AGENTS.md as a project-instruction fallback

Claude Code 2.1.277 can read AGENTS.md when a project has no CLAUDE.md. Teams maintaining instructions for several coding agents can reuse that project file instead of creating another copy solely for Claude Code. The setting is configurable under Project instructions, but the release notes exclude Bedrock, Vertex and Foundry from this initial support.

Anthropic · Sep 18, 2026

Why it matters

Helpful for repositories trying to keep agent setup and engineering conventions consistent across tools.

More context

This card covers the September 18 release entry. With an existing supported Claude Code account, update to a version containing the change and check Project instructions in /config. Test which instructions load in a small repository before removing duplicate files.

Keep in mind

This is fallback behavior, not a guarantee that every agent interprets AGENTS.md identically. Provider exclusions are explicit; 1min has not tested the release.

Original read