EffectPatterns MCP Server

Give your AI assistant access to 700+ Effect.ts patterns via the Model Context Protocol (MCP). Production API: https://effect-patterns-mcp.vercel.app

What is MCP?

The Model Context Protocol (MCP) is a standard for connecting AI assistants to external data sources and tools. The EffectPatterns MCP server exposes patterns, skills, and analysis rules as tools that any MCP-compatible client can use.

Supported Clients

CursorClaude DesktopClaude CodeWindsurfAny MCP Client

Setup

The MCP server runs from a local clone of the Effect-Patterns repo with Bun. Clone the repo and install dependencies:

git clone https://github.com/PaulJPhilp/Effect-Patterns.git

cd Effect-Patterns

bun install

Replace /absolute/path/to/Effect-Patterns in the config below with the actual path on your machine.

Cursor

Open Settings → MCP Servers and add:

{
  "mcpServers": {
    "effect-patterns": {
      "command": "bun",
      "args": ["--cwd", "packages/mcp-server", "dist/mcp-stdio.js"],
      "cwd": "/absolute/path/to/Effect-Patterns",
      "env": {
        "PATTERN_API_KEY": "your-api-key",
        "EFFECT_PATTERNS_API_URL": "https://effect-patterns-mcp.vercel.app"
      }
    }
  }
}

Claude Desktop

Open Settings → Developer → Model Context Protocol and add the same structure (command, args, cwd, env).

Windsurf

Create or edit .windsurf/mcp_config.json in your project with the same structure and add "disabled": false to the server entry.

Available Tools

search_patterns

Search the pattern library by keyword, category, and difficulty (params: q, category, difficulty, limit, format).

get_pattern

Get full documentation and code examples for a single pattern by ID (params: id, format).

list_analysis_rules

List all available code analysis rules (IDs, titles, severity, categories). No parameters.

list_skills

Search curated Effect-TS skill guides (params: q, category, limit, format).

get_skill

Get the full content of a specific skill guide by slug (params: slug, format).

Authentication

The MCP server sends your API key to the hosted API. Set PATTERN_API_KEY in the server env config (as in the setup examples above). The key is sent as x-api-key on requests.

Generate an API key from your account settings. Never commit API keys to version control.

Troubleshooting

Health check: curl https://effect-patterns-mcp.vercel.app/api/health
Authentication errors: verify PATTERN_API_KEY is set in the env your IDE passes to the MCP process.
Debug logging: set MCP_DEBUG=true in the server env for verbose output on stderr.