Cursor Rules: A Technical Deep Dive

Introduction

Cursor's rules system uses MDC (Model Context) files - markdown with optional YAML frontmatter. This architectural choice makes Cursor rules contextual, flexible, and persistent, providing reusable context at the prompt level.

Format Specification

File Location

Cursor rules live in .cursor/rules/:

MDC Frontmatter

According to the official Cursor documentation, the following frontmatter fields are supported:

PRPM's Implementation

Since Cursor uses the same markdown format as Claude (MDC with YAML frontmatter), PRPM aliases fromCursor to fromClaude. This reduces code duplication while maintaining format-specific handling when needed.

Best Practices

Be Specific, Not Generic

Include Rationale and Examples

Rules with rationale and concrete examples help AI understand not just what to do, but why. This leads to better code generation that aligns with your project's goals.

Cross-Format Conversion

PRPM enables seamless conversion between Cursor and other formats. When converting from Claude to Cursor, the frontmatter format is adjusted while preserving all content. When converting from Kiro to Cursor, file patterns are mapped to globs for conditional application.

Conclusion

Cursor's MDC format strikes a balance between structure (YAML frontmatter) and flexibility (Markdown body). PRPM's implementation fully supports Cursor's features including MDC frontmatter generation, glob pattern support, quality scoring for conversions, and comprehensive section mapping.