Claude Code has natively supported AGENTS.md since September 19. This is the project instruction file format launched by OpenAI in August 2025, essentially a Markdown file placed in the repository root—a README for AI, used to let coding assistants read a project's coding standards, build steps and testing requirements. Previously Claude Code insisted on reading only its own CLAUDE.md.
The problem is that the two files differ almost not at all in format or content. According to one sampling survey, 6.2% of active GitHub repositories contain AGENTS.md, while the share for CLAUDE.md is 5.4% (active repositories being defined as pushed within 90 days, non-fork, non-archived). In the same project, Codex and Cursor read AGENTS.md, while only Claude Code demands a separate CLAUDE.md; the two files overlap by about 90% yet must be maintained separately—and once one side is updated while the other is forgotten, different agents will give contradictory advice.
The community has therefore invented workarounds, but each has its costs. The most common is using symbolic links so both filenames point to the same content, but on Windows this requires administrator privileges or Developer Mode, and Git does not preserve symbolic links on Windows by default; when misconfigured, a cloned CLAUDE.md becomes an empty shell containing only the letters "AGENTS.md," which the agent reads as completely invalid without reporting any error. Some also use import syntax to read indirectly, but for new members, an instruction file with a single line pointing to another file of the same format is hard to understand.