Cursor Rules: Complete Guide to Customizing Your AI IDE

Cursor Rules shape how the AI behaves in your codebase. This guide explains how to write and use them effectively.

Quick Answer

Cursor Rules = instructions that tell Cursor how to code for your project. Put them in .cursorrules (project root) or Settings > Rules for AI (global). Use them for style, conventions, and constraints. Cursor

Where Rules Live

Project rules take precedence when both exist.

What to Put in Rules

Example .cursorrules

# Project: MyApp

- Next.js 15, TypeScript, Tailwind
- Use server components by default; add "use client" only when needed
- Write tests in Vitest; colocate with src
- No console.log in production code
- Follow our existing API patterns in /lib/api

Best Practices

Rules vs Other Context

• Rules: Persistent instructions; always in context.
• @-mentions: One-off context (files, docs, web).
• Chat history: Conversational context.

Rules set the baseline; @-mentions add task-specific context.

Common Patterns

• Language/framework: "TypeScript strict. React 19."
• Testing: "Jest/Vitest. Aim for 80% coverage on new code."
• Security: "No hardcoded secrets. Use env vars."
• Architecture: "Feature folders. No circular imports."

Next Steps

• How to use Cursor — Cursor basics.
• Cursor review 2026 — Full Cursor assessment.
• Cursor — Tool page.