What is AGENTS.md and Why is it the Open Universal Standard?
Historically, every AI tool introduced its own proprietary rule format: Cursor used `.cursorrules`, Claude Code introduced `CLAUDE.md`, GitHub Copilot uses `.github/copilot-instructions.md`, and Windsurf uses `.windsurfrules`.
`AGENTS.md` (standardized at agents.md) is the open, universal markdown specification supported across OpenAI Codex, Cursor, Sourcegraph Amp, Aider, Jules, RooCode, and Claude. Placing an `AGENTS.md` in your repo root gives all current and future AI agents a single source of truth.