Fast MCP is a Ruby library that simplifies integrating AI models into Ruby applications by implementing the Model Context Protocol (MCP). It targets Ruby developers seeking to connect LLMs to their applications, enabling AI models to securely call Ruby functions and access application data without complex protocol handling.

How It Works

Fast MCP provides a server implementation that registers "Tools" (Ruby methods callable by AI) and "Resources" (data accessible by AI). Tools define their arguments using dry-schema for robust validation. Resources expose data via URIs and content definitions. The library supports multiple transport mechanisms (STDIO, HTTP, SSE) and integrates seamlessly with Ruby web frameworks like Rails and Sinatra via Rack middleware.

Quick Start & Requirements

• Install: bundle add fast-mcp
• Rails: bin/rails generate fast_mcp:install
• Requirements: Ruby 3.2+
• Testing: npx @modelcontextprotocol/inspector <path/to/ruby_file.rb>
• Docs: Getting Started, Integration Guide

Highlighted Details

• Securely exposes Ruby functions to AI models via a Tools API with dry-schema validation.
• Allows AI models to access application data through a Resources API.
• Supports STDIO, HTTP, and SSE transports for flexible integration.
• Offers seamless integration with Rails, Sinatra, and other Rack applications.
• Includes DNS rebinding protection and token-based authentication for security.

Maintenance & Community

The project is actively maintained by yjacquin. Contributions are welcomed via pull requests.

Licensing & Compatibility

Licensed under the MIT License, permitting commercial use and integration with closed-source applications.

Limitations & Caveats

The project relies on Ruby 3.2+ and its core functionality is tied to the Model Context Protocol specification. Specific framework integrations (e.g., Hanami) are mentioned but may require deeper inspection for full compatibility.