Agent RulesAgent Rules
Comparison Guide

Cursor Rules vs CLAUDE.md vs Copilot Instructions

Every major AI coding assistant reads a different rules file. The concept is identical — a Markdown file that teaches your AI how to code for your project — but the filename, location, and features differ.

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Format Comparison

All six major AI coding assistant rules formats, side by side.

ToolFilenameAuto-loaded
Cursor.cursorrules
Claude CodeCLAUDE.md
GitHub Copilot.github/copilot-instructions.md
Windsurf.windsurfrules
OpenAI CodexAGENTS.md
Gemini CLIGEMINI.md

All formats use plain Markdown. Content can be identical — only the filename and location differ.

Key Differences

Cursor

.cursorrules

Also supports .cursor/rules/*.mdc for per-file-type rules

Claude Code

CLAUDE.md

Reads parent-directory CLAUDE.md files recursively up

GitHub Copilot

.github/copilot-instructions.md

Applied to every Copilot Chat session in the repository

Windsurf

.windsurfrules

Codeium's AI editor, direct Cursor competitor

OpenAI Codex

AGENTS.md

Includes setup commands, test commands, and constraints

Gemini CLI

GEMINI.md

Google's terminal coding agent powered by Gemini

Which Should You Use?

The short answer: use whichever file your AI tool reads. You can use all of them at once.

You use Cursor as your primary editor→ .cursorrules (or .cursor/rules/ for scoped rules)
You use Claude Code in the terminal→ CLAUDE.md
Your team uses GitHub Copilot across the repo→ .github/copilot-instructions.md
You use Windsurf→ .windsurfrules
You use multiple AI tools→ All of the above — they coexist peacefully in the same repo
You want one rules source for all tools→ Generate once in Agent Rules Builder and export to every format

Using Multiple AI Tools?

You can safely commit all rules files to the same repository. Each AI tool reads its own file and ignores the rest. A typical project with multiple AI tools might contain:

├──.cursorrules
├──CLAUDE.md
├──.github/copilot-instructions.md
├──.windsurfrules
├──AGENTS.md
├──GEMINI.md

Agent Rules Builder generates all formats from a single rules session — pick your stack once, export to every format.

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Frequently Asked Questions

What is the difference between .cursorrules and CLAUDE.md?

.cursorrules is Cursor's rules file, injected into every AI request in the editor. CLAUDE.md is Claude Code's rules file, read before each terminal agent session. Both use plain Markdown but serve different tools.

Which rules file should I use: .cursorrules, CLAUDE.md, or copilot-instructions.md?

Use whichever matches the AI tool you use. If you use Cursor, use .cursorrules. If you use Claude Code, use CLAUDE.md. If you use GitHub Copilot, use .github/copilot-instructions.md. You can maintain all three — Agent Rules Builder lets you generate and export to any format from a single session.

Can I use .cursorrules and CLAUDE.md at the same time?

Yes. You can commit all three files (.cursorrules, CLAUDE.md, .github/copilot-instructions.md) to the same repository. Each AI tool reads only its own file and ignores the others.

Where do I put .cursorrules in my project?

Place .cursorrules in the root of your project (same level as package.json). Cursor also supports .cursor/rules/ for glob-scoped rules that apply only to specific file patterns.

Does GitHub Copilot use .cursorrules?

No. GitHub Copilot reads .github/copilot-instructions.md, not .cursorrules. Each AI coding tool uses its own rules file format.

Want the full breakdown?

Our in-depth guide covers advanced features — Cursor glob-scoped rules, CLAUDE.md memory integration, multi-tool sync strategies, and real-world examples.

Read the Full Guide