cursor-md

name	cursor-md
description	Create or update CURSOR.md files following best practices for optimal AI agent onboarding

User Input

$ARGUMENTS

You MUST consider the user input before proceeding (if not empty). User may specify:

• create - Create new CURSOR.md from scratch
• update - Improve existing CURSOR.md
• audit - Analyze and report on current CURSOR.md quality
• A specific path to create/update (e.g., src/api/CURSOR.md for directory-specific instructions)

Core Principles

LLMs are stateless: CURSOR.md is the only file automatically included in every conversation. It serves as the primary onboarding document for AI agents into your codebase.

The Golden Rules

1. Less is More: Frontier LLMs can follow ~150-200 instructions. Cursor's system prompt already uses ~50. Keep your CURSOR.md focused and concise.

2. Universal Applicability: Only include information relevant to EVERY session. Task-specific instructions belong in separate files.

3. Don't Use Cursor as a Linter: Style guidelines bloat context and degrade instruction-following. Use deterministic tools (prettier, eslint, etc.) instead.

4. Never Auto-Generate: CURSOR.md is the highest leverage point of the AI harness. Craft it manually with careful consideration.

Execution Flow

1. Project Analysis

First, analyze the current project state:

1. Check for existing CURSOR.md files:

   • Root level: ./CURSOR.md or .cursor/CURSOR.md
   • Directory-specific: **/CURSOR.md
   • Global user config: ~/.cursor/CURSOR.md

2. Identify the project structure:

   • Technology stack (languages, frameworks)
   • Project type (monorepo, single app, library)
   • Development tools (package manager, build system, test runner)

3. Review existing documentation:

   • README.md
   • CONTRIBUTING.md
   • package.json, pyproject.toml, Cargo.toml, etc.

2. Content Strategy (WHAT, WHY, HOW)

Structure CURSOR.md around three dimensions:

WHAT - Technology & Structure

• Technology stack overview
• Project organization (especially important for monorepos)
• Key directories and their purposes

WHY - Purpose & Context

• What the project does
• Why certain architectural decisions were made
• What each major component is responsible for

HOW - Workflow & Conventions

• Development workflow (bun vs node, pip vs uv, etc.)
• Testing procedures and commands
• Verification and build methods
• Critical "gotchas" or non-obvious requirements

3. Progressive Disclosure Strategy

For larger projects, recommend creating an agent_docs/ folder:

agent_docs/
  |- building_the_project.md
  |- running_tests.md
  |- code_conventions.md
  |- architecture_decisions.md

In CURSOR.md, reference these files with instructions like:

For detailed build instructions, refer to `agent_docs/building_the_project.md`

Important: Use file:line references instead of code snippets to avoid outdated context.

4. Quality Constraints

When creating or updating CURSOR.md:

1. Target Length: Under 300 lines (ideally under 100)
2. No Style Rules: Remove any linting/formatting instructions
3. No Task-Specific Instructions: Move to separate files
4. No Code Snippets: Use file references instead
5. No Redundant Information: Don't repeat what's in package.json or README

5. Essential Sections

A well-structured CURSOR.md should include:

# Project Name

Brief one-line description.

## Tech Stack
- Primary language and version
- Key frameworks/libraries
- Database/storage (if any)

## Project Structure
[Only for monorepos or complex structures]
- `apps/` - Application entry points
- `packages/` - Shared libraries

## Development Commands
- Install: `command`
- Test: `command`
- Build: `command`

## Critical Conventions
[Only non-obvious, high-impact conventions]
- Convention 1 with brief explanation
- Convention 2 with brief explanation

## Known Issues / Gotchas
[Things that consistently trip up developers]
- Issue 1
- Issue 2

6. Anti-Patterns to Avoid

DO NOT include:

• Code style guidelines (use linters)
• Documentation on how to use Cursor
• Long explanations of obvious patterns
• Copy-pasted code examples
• Generic best practices ("write clean code")
• Instructions for specific tasks
• Auto-generated content
• Extensive TODO lists

7. Validation Checklist

Before finalizing, verify:

• Under 300 lines (preferably under 100)
• Every line applies to ALL sessions
• No style/formatting rules
• No code snippets (use file references)
• Commands are verified to work
• Progressive disclosure used for complex projects
• Critical gotchas are documented
• No redundancy with README.md

Output Format

For create or default:

1. Analyze the project
2. Draft a CURSOR.md following the structure above
3. Present the draft for review
4. Write to the appropriate location after approval

For update:

1. Read existing CURSOR.md
2. Audit against best practices
3. Identify:
   • Content to remove (style rules, code snippets, task-specific)
   • Content to condense
   • Missing essential information
4. Present changes for review
5. Apply changes after approval

For audit:

1. Read existing CURSOR.md
2. Generate a report with:
   • Current line count vs target
   • Percentage of universally-applicable content
   • List of anti-patterns found
   • Recommendations for improvement
3. Do NOT modify the file, only report

AGENTS.md Handling

If the user requests AGENTS.md creation/update:

AGENTS.md is used for defining specialized agent behaviors. Unlike CURSOR.md (which is for project context), AGENTS.md defines:

• Custom agent roles and capabilities
• Agent-specific instructions and constraints
• Workflow definitions for multi-agent scenarios

Apply similar principles:

• Keep focused and concise
• Use progressive disclosure
• Reference external docs instead of embedding content

Notes

• Always verify commands work before including them
• When in doubt, leave it out - less is more
• The system reminder tells Cursor that CURSOR.md "may or may not be relevant" - the more noise, the more it gets ignored
• Monorepos benefit most from clear WHAT/WHY/HOW structure
• Directory-specific CURSOR.md files should be even more focused