MCP RB

What is MCP-RB?

MCP-RB is a lightweight Ruby framework for implementing MCP (Model Context Protocol) servers using a Sinatra-like DSL. It integrates with the MCP specification 2024-11-05 and is intended for Ruby developers who want to build MCP servers with minimal boilerplate.

How to use MCP-RB?

Install the gem by adding gem 'mcp-rb' to your Gemfile. In your server script, use the DSL to set the server name and version, then define resources, resource templates, and tools with their callbacks. Run the script directly via a Ruby interpreter; MCP-RB uses stdio transport out of the box.

Key features of MCP-RB

• Sinatra-like DSL for defining server capabilities
• Supports resources, resource templates, and tools
• Tools can accept nested and array arguments
• Implements base protocol (ping), resource endpoints (list, read, templates/list), and tool endpoints (list, call)
• Uses stdio transport only
• Lightweight, Ruby-native implementation

Use cases of MCP-RB

• Building a simple MCP server to expose static resources
• Creating tools that accept complex, structured arguments (e.g., nested hashes or arrays)
• Exposing dynamic, parameterized resources via resource templates
• Rapid prototyping of MCP servers in Ruby
• Testing MCP server behavior with the MCP Inspector tool