AGENTS.md
AGENTS.md is the project rules file that Codex and Cursor read, and that Claude Code reads too when no CLAUDE.md sits above it.
AGENTS.md is the same idea as CLAUDE.md, in the file that Codex and Cursor read. It sits in the project root and carries the stack, the commands, the conventions and the do-not rules.
Claude Code reads it too, but by default only when there is no CLAUDE.md or CLAUDE.local.md in your working directory or above it: AGENTS.md is its fallback, not a second file loaded alongside. If a CLAUDE.md sits above, set Project instructions to claude-md-and-agents-md in /config to read both, or import the file with a one-line CLAUDE.md that contains @AGENTS.md. Reading it directly needs Claude Code v2.1.277 or later. Generate a matching pair with the CLAUDE.md generator.
Checked against AGENTS.md read only when no CLAUDE.md/CLAUDE.local.md above; Project instructions in /config (2026-10-23) , Direct AGENTS.md reading added in Claude Code v2.1.277 (2026-10-23) .