Mastering Cursor Configuration: A Comprehensive Guide to Project Rules and Settings

I've spent countless hours exploring Cursor's configuration capabilities, and I'm excited to share what I've learned. Whether you're setting up a new project or optimizing an existing one, understanding Cursor's configuration system can significantly enhance your development workflow.

Understanding Cursor's Configuration Structure

Project Structure

The recommended structure for a Cursor-configured project looks like this:

mi-project/
├── .cursor/                   # Cursor configuration folder
│   ├── rules/                 # Project rules
│   │   ├── base.mdc          # Base rules (always applied)
│   │   ├── python-rules.mdc  # Python-specific rules
│   │   ├── react-rules.mdc   # React-specific rules
│   │   └── security.mdc      # Security rules
│   ├── mcp/                  # MCP server configurations
│   │   ├── db-server.mcpjson # Database connection config
│   │   └── api-server.mcpjson # API connection config
│   └── docs/                 # Project documentation
│       └── project-context.md # Project context for the agent

Types of Rules in Cursor

Cursor offers four different types of rules, each serving a specific purpose:

1. Always Rules

These rules are automatically added to every AI request to ensure standardized responses. Perfect for:

• Project-wide coding standards
• Required libraries and versions
• General architectural guidelines

Example:

---
title: "Base Project Rules"
id: base-rules
description: "General coding rules for the entire project"
priority: 100
---

- Follow PEP 8 for Python and Airbnb style guide for JavaScript
- All functions must have docstring documentation
- No global variables
- 80-character line limit
- All files must have corresponding unit tests

2. Auto-Attach Rules

These rules are automatically applied based on file extensions. Great for:

• Language-specific conventions
• Framework-specific patterns
• File-type specific requirements

Example:

---
title: "Python Rules"
id: python-rules
description: "Python-specific coding standards"
globs: "**/*.py"
---

- Use type hints for all function parameters
- Follow Google-style docstrings
- Maximum function length: 50 lines

3. Agent-Requested Rules

These rules are applied only when the agent determines they're relevant. Useful for:

• Security guidelines
• Performance optimization rules
• Complex architectural decisions

Example:

---
title: "Security Rules"
id: security-rules
description: "Security best practices for the project"
---

- Never store sensitive data in code
- Use environment variables for secrets
- Implement proper input validation

4. Manual Rules

These rules are applied only when explicitly referenced. Good for:

• Temporary guidelines
• Experimental features
• Project-specific exceptions

Configuring MCP Servers

MCP (Model Context Protocol) servers allow Cursor to interact with external systems. Here's how to set them up:

Basic MCP Configuration

{
  "name": "database-server",
  "type": "postgres",
  "connection": {
    "host": "localhost",
    "port": 5432,
    "database": "myapp"
  }
}

Common MCP Use Cases

1. Database connections
2. API integrations
3. External service access
4. Custom tool integration

Best Practices for Cursor Configuration

1. Start with Base Rules

Begin with fundamental rules that apply to your entire project:

• Coding standards
• Documentation requirements
• Testing requirements
• Security guidelines

2. Use Globs Effectively

The globs field in rules helps target specific files:

globs: "**/*.rb"              # All Ruby files
globs: "**/db/migrate/*.rb"   # Only DB migration files
globs: "app/controllers/**/*.rb" # Ruby files in controllers

3. Organize Rules by Purpose

• Keep related rules together
• Use clear, descriptive names
• Include helpful descriptions
• Set appropriate priorities

4. Version Control Your Configuration

• Commit all .cursor directory contents
• Document rule changes
• Review configuration changes in PRs
• Keep configurations in sync across team

Advanced Configuration Tips

1. Rule Priorities

Use the priority field to control rule application order:

---
priority: 100  # Higher numbers = higher priority
---

2. Context Management

• Use the docs folder for project context
• Keep documentation up to date
• Include relevant examples
• Document edge cases

3. Security Considerations

• Never include sensitive data in rules
• Use environment variables
• Implement proper access controls
• Regular security reviews

Troubleshooting Common Issues

1. Rules Not Applying

• Check file extensions match globs
• Verify rule priority
• Ensure proper file structure
• Check for syntax errors

2. MCP Connection Issues

• Verify connection details
• Check network access
• Validate credentials
• Review server logs

3. Performance Optimization

• Keep rules focused and specific
• Avoid redundant rules
• Use appropriate glob patterns
• Regular cleanup of unused rules

Conclusion

Cursor's configuration system is powerful and flexible, allowing you to create a development environment that perfectly matches your team's needs. By following these guidelines and best practices, you can create a robust, maintainable, and efficient development workflow.

Remember that configuration is an ongoing process. Regularly review and update your rules to ensure they continue to serve your team's needs effectively.

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This guide is based on current Cursor capabilities. As the tool evolves, some features and best practices may change. Always refer to the official documentation for the most up-to-date information.