MCPatterns

MCPatterns is a Model Context Protocol (MCP) server that enables users to save and retrieve personalized coding patterns. It helps LLMs learn how an individual codes by storing structured patterns categorized by technology, use case, and style.

🧠 Purpose

This server acts as a persistent memory layer for LLM agents, allowing them to reference a user's preferred coding styles, patterns, and conventions. It supports:

• Personalized code generation based on stored patterns
• Consistent refactoring following user preferences
• Style-aware suggestions using familiar patterns
• Long-term memory of coding practices across sessions

🧩 MCP Integration

MCPatterns follows the Model Context Protocol specification, providing tools for creating, reading, updating, and deleting coding patterns. It uses JSONL (newline-delimited JSON) storage for atomic operations and data consistency.

🗂 Pattern Schema

interface Pattern {
  name: string;                              // Unique identifier
  category: string;                          // e.g., "Backend", "Frontend", "Database"
  description: string;                       // What this pattern does
  use_cases: string[];                       // When to use this pattern
  technologies: string[];                    // Languages, frameworks, libraries
  code_examples: { [language: string]: string }; // Code samples by language
}

Example Pattern

{
  "name": "Error Handling Middleware",
  "category": "Backend",
  "description": "Express middleware for consistent error handling with structured responses",
  "use_cases": ["API development", "Middleware composition", "Error standardization"],
  "technologies": ["Node.js", "Express", "TypeScript"],
  "code_examples": {
    "JavaScript": "app.use((err, req, res, next) => {\n  console.error(err.stack);\n  res.status(500).json({ error: 'Something went wrong!' });\n});",
    "TypeScript": "app.use((err: Error, req: Request, res: Response, next: NextFunction) => {\n  console.error(err.stack);\n  res.status(500).json({ error: 'Something went wrong!' });\n});"
  }
}

🔧 Available Tools

MCPatterns provides the following MCP tools:

create_patterns

Create multiple new coding patterns in the database.

Input:

{
  "patterns": [Pattern, ...]
}

add_code_examples

Add new code examples to existing patterns.

Input:

{
  "additions": [
    {
      "patternName": "string",
      "examples": { "language": "code" }
    }
  ]
}

delete_patterns

Delete multiple patterns by name.

Input:

{
  "patternNames": ["pattern1", "pattern2"]
}

delete_code_examples

Remove specific code examples from patterns.

Input:

{
  "deletions": [
    {
      "patternName": "string",
      "languages": ["JavaScript", "TypeScript"]
    }
  ]
}

read_patterns

Retrieve all stored patterns.

Input: None

search_patterns

Search patterns by query across all fields.

Input:

{
  "query": "search term"
}

open_patterns

Retrieve specific patterns by name.

Input:

{
  "names": ["pattern1", "pattern2"]
}

🗄 Storage

MCPatterns uses JSONL (newline-delimited JSON) format for data storage:

• File location: Configurable via PATTERNS_FILE_PATH environment variable
• Default location: patterns.json in the server directory
• Format: Each line contains a JSON object with type: "pattern"
• Atomic operations: Full file rewrite ensures data consistency

🚀 Getting Started

Installation

git clone https://github.com/nicholasrubright/mcpatterns.git
cd mcpatterns
pnpm install

Development

pnpm run dev

Building

pnpm run build

Running

pnpm start
# or
mcpatterns

🔧 Configuration

Environment Variables

• PATTERNS_FILE_PATH: Custom path for the patterns database file
  • Can be absolute path or relative to script directory
  • Defaults to patterns.json in server directory

Claude Desktop Integration

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "mcpatterns": {
      "command": "npx",
      "args": ["-y", "@mcpatterns/server"]
    }
  }
}

With Custom Storage Path

{
  "mcpServers": {
    "mcpatterns": {
      "command": "npx",
      "args": ["-y", "@mcpatterns/server"],
      "env": {
        "PATTERNS_FILE_PATH": "/path/to/custom/patterns.json"
      }
    }
  }
}

VS Code Integration

Add to your VS Code settings (settings.json):

{
  "mcp": {
    "servers": {
      "mcpatterns": {
        "command": "npx",
        "args": ["-y", "@mcpatterns/server"]
      }
    }
  }
}

💡 Usage Tips

For LLM Agents

MCPatterns works best when integrated into your AI workflow with prompts like:

Before generating code, search my patterns for relevant examples using the technologies I'm working with. Use my established patterns and coding style preferences when creating new code.

Pattern Organization

• Use descriptive names that clearly identify the pattern's purpose
• Group related patterns with consistent category naming
• Include comprehensive use cases to improve searchability
• Provide examples in multiple languages when applicable

Best Practices

• Atomic patterns: Store focused, single-purpose patterns
• Rich metadata: Include detailed use cases and technology tags
• Version examples: Keep code examples up-to-date with current practices
• Search-friendly: Use descriptive language in descriptions and use cases

📜 License

MIT