Anthropic has added support for AGENTS.md files to Claude Code, version 2.1.277. When the tool scans a project directory, it now checks for this specific file if the standard CLAUDE.md is absent. The feature extends the existing mod system, allowing developers to define custom project instructions without writing code. Users can access the source for this built-in modification on the GitHub repository for the project.
This update shifts how developers configure context for their codebase. Instead of relying solely on a single markdown file, teams can now layer instructions directly into the agent’s workflow. The change integrates with the upcoming custom mod framework, meaning users will eventually be able to create their own versions of these instructions. This approach reduces the friction of setting up new development environments where specific guidelines must be manually inserted.