Which files does each AI coding agent read?

Most agents read AGENTS.md: Cursor, Devin, GPT-5 Codex, Kimi CLI, OpenHands, and Pi. Claude Code reads CLAUDE.md and falls back to AGENTS.md. Gemini CLI and Aider read their own files, and AGENTS.md only when configured to.

Which files does each agent read?

Repo files each AI coding agent reads
Agent	Reads from the repo	Notes
Claude Code	`CLAUDE.md` `.claude/CLAUDE.md` `CLAUDE.local.md` `AGENTS.md`	Reads AGENTS.md only when no CLAUDE.md is found (v2.1.277 and later). A CLAUDE.md that starts with `@AGENTS.md` loads both. code.claude.com/memory
Cursor	`.cursor/rules/*.mdc` `AGENTS.md` `.cursorrules`	Project rules live in `.cursor/rules/`; `.cursorrules` is the deprecated single-file form. cursor.com/rules
Devin	`AGENTS.md`	Looks for AGENTS.md before it starts coding and includes its first 16 KiB. Setup comes from its environment snapshot. docs.devin.ai/environment docs.devin.ai/agents-md
GPT-5 Codex	`AGENTS.md` `AGENTS.override.md`	Reads AGENTS.md before any work, including one per directory; AGENTS.override.md takes precedence. learn.chatgpt.com/agents-md
Kimi CLI	`AGENTS.md` `.kimi-code/AGENTS.md`	`/init` writes an AGENTS.md. Its docs name no CLAUDE.md fallback. github.com/agents.md github.com/slash-commands.md
Gemini CLI	`GEMINI.md`	Reads GEMINI.md at every level from global to per-directory. AGENTS.md loads once it is listed in the `context.fileName` setting. geminicli.com/gemini-md
Aider	`.aider.conf.yml`	Reads AGENTS.md or CONVENTIONS.md only when `.aider.conf.yml` lists it under `read:`. aider.chat/lint-test.html aider.chat/aider_conf.html
OpenHands	`AGENTS.md` `.openhands/setup.sh` `.agents/skills/`	Runs `.openhands/setup.sh` in its sandbox when a session starts. docs.openhands.dev/repository docs.openhands.dev/skills
Pi	`AGENTS.md` `CLAUDE.md`	Loads either name from the working directory and every directory above it. github.com/configuration.md

How do I write one file every agent reads?

Write it in AGENTS.md at the repo root. What to put in it.
If you keep a CLAUDE.md, start it with @AGENTS.md, or Claude Code skips AGENTS.md. AGENTS.md vs CLAUDE.md.
Aider: list AGENTS.md under read: in .aider.conf.yml. Gemini CLI: add it to context.fileName, or keep a GEMINI.md.
Cursor-only rules go in .cursor/rules/, OpenHands setup in .openhands/setup.sh.

How many repos have each file?

AGENTS.md197 of 401 (49%)
CLAUDE.md19 of 401 (5%)
.cursor/rules or .cursorrules18 of 401 (4%)
GEMINI.md8 of 401 (2%)
.openhands/setup.sh2 of 401 (0.5%)
.aider.conf.yml1 of 401 (0.2%)

A repo with both files counts under AGENTS.md unless it is empty; empty files don't count. Read the files.

Agent names link to their boards. The methodology has every weight.