Claude Code adds AGENTS.md fallback support
Original: Claude Code now reads AGENTS.md if there is no Claude.md
Why This Matters
Cross-agent instruction compatibility reduces friction for teams running multiple AI coding tools side by side.
Claude Code now reads AGENTS.md when no CLAUDE.md file is present in a project. The change, noted in the official changelog, gives teams using OpenAI Codex or other agent frameworks a compatibility path without duplicating instruction files.
Anthropic quietly added a fallback behavior to Claude Code: if no CLAUDE.md file exists in the working directory, the tool will now read AGENTS.md instead. CLAUDE.md is Claude Code's native file for storing persistent instructions—coding conventions, project context, preferred workflows—that the agent picks up at the start of each session. AGENTS.md, by contrast, is the convention popularized by OpenAI's Codex agent. The change means teams that already maintain an AGENTS.md for other AI coding tools don't need to create a separate CLAUDE.md to get Claude Code to respect project-level instructions. The update was documented in the Claude Code changelog without fanfare, listed among a long series of incremental version bumps. No additional configuration is required; the fallback activates automatically when CLAUDE.md is absent.