CLAUDE.md, AGENTS.md, GEMINI.md: which tool reads which file

Ahmet Karaca · 30 October 2026

Which file does each tool read?

Each file has its own guide: CLAUDE.md, AGENTS.md, Cursor rules, Copilot instructions and GEMINI.md.

How can several tools share one file?

Keeping the shared instructions in AGENTS.md reaches most tools without copies. Two of them need one extra step.

Claude Code reads AGENTS.md by itself only when the project has no CLAUDE.md. If it does, a CLAUDE.md that imports the shared file gives Claude both, with room for anything specific to Claude Code:

@AGENTS.md

## Claude Code

Use plan mode for changes under src/billing/.

A symbolic link from CLAUDE.md to AGENTS.md also works, but the documentation advises the import when anyone on the project uses Windows, where such links need Administrator rights or Developer Mode.

Gemini CLI needs its file name set in settings.json:

{
  "context": {
    "fileName": ["AGENTS.md", "GEMINI.md"]
  }
}

What belongs in the project file, and what in the personal one?

The project file holds what is true of the code for anyone working on it: commands, conventions, files not to touch. It is committed and shared. The personal file holds how you prefer to work, and it follows you into every project without being imposed on your colleagues.

A preference committed to a shared repository becomes everyone's instruction, and a project command kept in a personal file is missing for everyone else.

Why does a file sometimes have no effect?

These files are context for the model, not enforced settings, so the first step is to confirm that the file loaded: /context in Claude Code, /memory show in Gemini CLI. The causes and checks for Claude Code are in the guide on an ignored CLAUDE.md.

Sources, checked on 30 October 2026

• Claude Code docs: AGENTS.md and CLAUDE.md
• OpenAI: Custom instructions with AGENTS.md
• Cursor docs: Rules
• VS Code: Custom instructions
• Gemini CLI docs: GEMINI.md files