Cursor Rules: Pay More Upfront, Iterate Less Later

**TL;DR**: The hybrid rules approach that saves 70% on context loading and completes tasks in fewer iterations. --- ## Your Cursor AI is Loading Too Much Every time you ask Cursor for help, it loads your entire `.cursorrules` file—even when most rules aren't relevant. **The result?** - Slower responses (processing 5,000+ unnecessary tokens) - Wasted context budget on rules you don't need - Loading test patterns when writing docs **There's a better way.** --- ## The Hybrid Approach Split your rules into two parts: ### 1. **AGENTS.md** (always loaded) Lightweight file with core principles that apply to every task. ### 2. **.cursor/rules/** (loaded intelligently) Detailed patterns that load only when relevant to your current file. --- ## Quick Example **AGENTS.md** (in project root): ```markdown # My TypeScript Project ## Core Workflow 1. RED → Write failing test 2. GREEN → Minimal implementation 3. REFACTOR → Improve quality ## Critical Rules - Tests before implementation - TypeScript strict mode - 80% test coverage ## See Rules Details: @tdd-workflow @testing ``` **.cursor/rules/testing.mdc**: ```markdown --- description: "Testing patterns and best practices" globs: ["**/*.test.ts"] --- # Testing Standards [Detailed test patterns, examples, edge cases...] ``` **What happens?** - Cursor always knows your TDD workflow - When you edit test files, detailed patterns auto-load - When you edit docs, testing rules stay dormant - You get smart guidance without constant overhead --- ## Get Started in 5 Minutes **Step 1: Create AGENTS.md** ```markdown # [Your Project] ## Workflow [Your main development process] ## Critical Rules [Top 3-5 non-negotiable rules] ## See Rules @rule-name-1 @rule-name-2 ``` **Step 2: Create .cursor/rules/** ```bash mkdir -p .cursor/rules ``` **Step 3: Add focused rule files** ```markdown --- description: "Testing patterns" globs: ["**/*.test.ts"] --- # Your detailed testing rules here ``` **Pro tip**: Keep AGENTS.md under 50 lines. Everything else goes in `.cursor/rules/`. --- ## The Token Trade-off: More Upfront, Less Overall **Here's the honest truth**: Agent Mode with rules uses **MORE tokens per session** but **FEWER total tokens** to complete your task. **Without Rules:** ``` Attempt 1: 20K tokens → Wrong architecture Attempt 2: 30K tokens → Tests need fixing Attempt 3: 25K tokens → Finally correct Total: ~75K tokens + frustration + your time ``` **With Rules:** ``` Attempt 1: 70k-100k tokens → Done correctly Total: ~100K tokens + confidence ``` ### When to Use Rules **Use Agent Mode + Rules when:** - Building production features - Architecture compliance matters - Consistency is critical - Your time is valuable **Skip Rules when:** - Quick prototypes - Exploring ideas - Simple one-line changes - You know exactly what to do ### The Smart Workflow **Phase 1: You Think (No Agent Mode)** - Write down requirements - Identify edge cases - Plan architecture - Token cost: Minimal **Phase 2: Agent Implements (With Rules)** - Provide your spec - Let AI execute with precision - Review at checkpoints - Token cost: Higher, but efficient **Key insight**: Rules don't replace your thinking—they ensure AI implements YOUR design correctly. --- ## ⚠️ Repository-Specific Rules Matter **Don't copy-paste rules between projects.** Each repository has unique: - File organization patterns - Testing strategies - Architecture decisions - Team conventions **Example:** ``` React Frontend: src/components/, src/hooks/, __tests__/ CLI Tool: src/commands/, src/services/, test/ Monorepo: apps/, packages/, libs/ → Different structures = Different rules ``` Think of rules as a **custom onboarding document** for each repo. Invest 30 minutes per project to create tailored rules that reflect how THAT specific codebase works. --- ## Key Principles for Success ### 1. Keep AGENTS.md Minimal **Under 50 lines** with only what applies to 80%+ of tasks. ### 2. Make Rules Focused **One concern per file**: testing.mdc, architecture.mdc, not everything.mdc ### 3. Use Smart Loading ```markdown --- description: "What this covers" globs: ["**/*.test.ts"] # Auto-load for test files alwaysApply: false # Don't load everywhere --- ``` ### 4. Examples Over Essays Show one good pattern. AI learns from code, not paragraphs. --- ## What You'll Gain **Before (single .cursorrules):** - Slower responses - Context budget wasted **After (hybrid approach):** - Faster AI responses - Rules load only when relevant **But remember**: Agent Mode trades upfront tokens for fewer iterations. You spend more per session, but complete tasks in 1-2 tries instead of 5+. --- ## Your Next Action 1. Create `AGENTS.md` with your top 5 rules **today** 2. Move detailed patterns to `.cursor/rules/` 3. Test it: Ask Cursor to build something and watch it follow your workflow automatically Your AI pair programmer will be smarter, faster, and more aligned with your team's patterns. --- **Resources:** - [Cursor Rules Docs](https://cursor.com/docs/context/rules) - [Awesome Cursor Rules](https://github.com/PatrickJS/awesome-cursorrules)