Claude Code Adds AGENTS.md Support, Reducing the Need to Maintain a Separate CLAUDE.md

September 19, 2026Updated: September 19, 2026Articles

Anthropic released Claude Code 2.1.277 on September 18, 2026, adding the ability to read AGENTS.md as a project instruction file.

AGENTS.md is a Markdown file for recording setup steps, test commands, coding conventions, and other instructions for AI coding agents. It is already supported by Codex and several other tools. Claude Code can now use the same file.

Here is what changed, what was inconvenient before, and how this update helps people who use more than one coding agent.

Claude Code 2.1.277 can read AGENTS.md directly

By default, Claude Code reads AGENTS.md as its project instructions when there is no CLAUDE.md or CLAUDE.local.md in the working directory or any directory above it.

Files in the project	What Claude Code reads by default
Only `AGENTS.md`	`AGENTS.md`
`AGENTS.md` and `CLAUDE.md`	`CLAUDE.md`
`CLAUDE.md` imports `@AGENTS.md`	Both, through `CLAUDE.md`

To have Claude Code always read both files, open /config and change “Project instructions” to claude-md-and-agents-md.

Previously, Claude Code needed its own CLAUDE.md

Until now, CLAUDE.md was the standard project instruction file read by Claude Code. Even if a project already had an AGENTS.md for Codex or another tool, you had to prepare one of the following for Claude Code:

Copy the same instructions into CLAUDE.md
Import @AGENTS.md from CLAUDE.md
Make CLAUDE.md a symbolic link to AGENTS.md

Keeping the same content in two files also created a risk that one file would be updated while the other was left unchanged. Opening an existing repository in Claude Code could require adding a tool-specific file first.

It is now easier to share instructions across coding agents

With this update, Codex and Claude Code can follow the same instructions in a project that only contains AGENTS.md. Test procedures, files that must not be edited, and commit rules can be maintained in one place.

Claude Code also loads an AGENTS.md in a subdirectory when it opens a file there. This supports larger repositories where the frontend and backend need different instructions.

Check the behavior when a project already has CLAUDE.md

Support for AGENTS.md does not mean Claude Code reads both files by default. If a project already has CLAUDE.md, Claude Code continues to prioritize that file.

If you want shared instructions in AGENTS.md and Claude Code-specific instructions in CLAUDE.md, you can keep importing @AGENTS.md from CLAUDE.md. You can also change “Project instructions” so Claude Code reads both files.

Direct loading requires Claude Code 2.1.277 or later. According to the official documentation, AGENTS.md may not be loaded during the first session after installing or upgrading, and becomes available from the next session. As of September 19, 2026, it is also unavailable in some environments, including sessions that use Amazon Bedrock, Google Vertex AI, or Microsoft Foundry.

AI Jiten’s view: fewer instructions to rewrite when switching tools

This update does not improve Claude Code’s code-generation ability. It does make instruction-file management simpler for people who use Codex and Claude Code in the same project.

I also switch between multiple coding agents depending on the task. If project-specific rules can live in AGENTS.md and every compatible tool reads the same content, I do not need to repeat the same explanation each time I switch tools.

There is no need to force Claude Code-specific features and operating rules into the shared file. A practical approach is to put common instructions in AGENTS.md and add CLAUDE.md only when Claude Code needs additional guidance.

Summary

Claude Code 2.1.277 can read AGENTS.md directly as project instructions when the project does not have CLAUDE.md. For some projects, this removes the need to copy instructions, add an import, or create a symbolic link.

If CLAUDE.md already exists, Claude Code prioritizes it by default. To use both files, keep the existing @AGENTS.md import or change the Project instructions setting in Claude Code.