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AI Coding Instruction Files Explained
Overview of AI coding instruction files including AGENTS.md, CLAUDE.md, GEMINI.md, and Copilot instructions, with a comparison table.
Last updated: March 15, 2026
TL;DR
- AI coding instruction files give agents repository-specific guidance.
- Common files include AGENTS.md, CLAUDE.md, GEMINI.md, and Copilot instructions.
- A comparison table helps teams decide which files to standardize first.
What are AI coding instruction files?
AI coding instruction files are text files checked into a repository that describe how AI coding assistants should behave in that project. They provide persistent guidance about coding style, testing rules, review expectations, and workflows.
Different tools consume different file names, but the core idea is the same: treat instructions as configuration that can be versioned, reviewed, and rolled out like any other change.
How does AGENTS.md fit into instruction files?
AGENTS.md is a cross-tool instruction file used by several AI coding agents. It aims to be a shared standard for repository-level instructions so teams do not have to maintain separate files for every tool.
For a deeper dive, see What Is AGENTS.md?.
How do CLAUDE.md, GEMINI.md, and Copilot instructions compare?
Some tools ship their own file names. Claude Code reads CLAUDE.md, Gemini tooling reads GEMINI.md, and GitHub Copilot looks at specific instruction paths. Each file targets one tool but often carries overlapping content.
| File | Primary tool | Scope |
|---|---|---|
| AGENTS.md | Multiple coding agents | Cross-tool repository standard |
| CLAUDE.md | Claude Code | Claude-specific instructions |
| GEMINI.md | Gemini CLI and tools | Gemini-specific instructions |
| Copilot instructions | GitHub Copilot | Copilot-specific instructions |
FAQ
Do we need every instruction file type in every repo?
Not necessarily. Many teams standardize on AGENTS.md as a cross-tool baseline and then add CLAUDE.md, GEMINI.md, or Copilot-specific files where they use those tools heavily. The important part is having a clear standard rather than a random mix.