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model-context-protocol-rb

An implementation of the Model Context Protocol (MCP) in Ruby.

Provides simple abstractions that allow you to serve prompts, resources, resource templates, and tools via MCP locally (stdio) or in production (streamable HTTP backed by Redis) with minimal effort.

Getting Started

1. Installation - Add the gem to your project
2. Building an MCP Server - Configure and run your MCP server
3. Quick Start with Rails - Full Rails integration example

Documentation

Server Handlers

• Prompts - Define prompts that MCP clients can use to generate contextual messages
• Resources - Expose data and content to MCP clients
• Resource Templates - Define parameterized resources with URI templates
• Tools - Create callable functions that MCP clients can invoke
• Completions - Provide argument completion hints for prompts and resources

Testing

• Testing with RSpec - Custom matchers and helpers for testing your MCP handlers

Feature Support

Status	Feature
✅	Prompts
✅	Resources
✅	Resource Templates
✅	Tools
✅	Completion
✅	Logging
✅	Pagination
✅	Environment Variables
✅	STDIO Transport
✅	Streamable HTTP Transport
✅	Cancellation
✅	Ping
✅	Progress
❌	List Changed Notification (Prompts)
❌	List Changed Notification (Resources)
❌	Subscriptions (Resources)
❌	List Changed Notification (Tools)

Links

• GitHub Repository
• RubyGems
• MCP Specification