Ruby SDK
[Rust MCP SDK](https://github.com/modelcontextprotocol/rust-sdk)
What is Ruby SDK?
Ruby SDK is a Model Context Protocol (MCP) server that allows AI assistants like Claude, Cursor, and VS Code to [rust mcp sdk](https://github.com/modelcontextprotocol/rust-sdk)
[Rust MCP SDK](https://github.com/modelcontextprotocol/rust-sdk)
This server falls under the Developer Tools category on MCPgee, the world's largest MCP server directory with 33,000+ servers.
Features
- MCP protocol support
Use Cases
Maintainer
Works with
Installation
Manual Installation
npx ruby-sdkConfiguration
Configuration Details
claude_desktop_config.json
Performance
Response Metrics
Resource Usage
How to Set Up and Use Ruby SDK
The MCP Ruby SDK is the official Ruby implementation of the Model Context Protocol, enabling Ruby developers to build both MCP servers and clients with full support for tools, prompt templates, resources, real-time notifications, OAuth 2.1 authorization, and multiple transports including stdio and Streamable HTTP with SSE. It is the foundation for building Ruby-based MCP integrations — from Rails-mounted HTTP servers to standalone script-based tools — and is distributed as the `mcp` gem through RubyGems.
Prerequisites
- Ruby 3.1+ installed on your machine
- Bundler gem installed (`gem install bundler`)
- An MCP-compatible client (Claude Desktop, Cursor, etc.) if you want to connect to a server you build
- Rails 7+ (optional, required only for the HTTP/SSE transport mounting pattern)
Add the mcp gem to your project
Add the gem to your Gemfile and install it, or install directly for quick experimentation.
# In your Gemfile:
gem 'mcp'
# Then install:
bundle install
# Or install globally:
gem install mcpDefine a tool class
Create a Ruby class that inherits from MCP::Tool. Define a description, input schema, and a call method that returns an MCP::Tool::Response.
class GreetTool < MCP::Tool
description "Greet a user by name"
input_schema(
properties: { name: { type: "string", description: "Name to greet" } },
required: ["name"]
)
def self.call(name:, server_context:)
MCP::Tool::Response.new([{ type: "text", text: "Hello, #{name}!" }])
end
endCreate and start a stdio MCP server
Wire up the tool to an MCP::Server and start it with the stdio transport — the standard pattern for MCP clients that spawn the server as a subprocess.
server = MCP::Server.new(name: "my_ruby_server", tools: [GreetTool])
transport = MCP::Server::Transports::StdioTransport.new(server)
transport.openRegister the server in your MCP client configuration
Add an entry to claude_desktop_config.json pointing to your Ruby server script.
{
"mcpServers": {
"my-ruby-server": {
"command": "bundle",
"args": ["exec", "ruby", "/path/to/your/server.rb"]
}
}
}Mount on Rails with HTTP transport (optional)
For HTTP-based deployments, create a StreamableHTTPTransport and mount it in your Rails routes for persistent server-sent event connections.
# config/routes.rb
server = MCP::Server.new(name: "rails_mcp", tools: [GreetTool])
transport = MCP::Server::Transports::StreamableHTTPTransport.new(server)
Rails.application.routes.draw { mount transport => "/mcp" }Ruby SDK Examples
Client configuration
claude_desktop_config.json entry for a Ruby MCP server run with Bundler.
{
"mcpServers": {
"my-ruby-server": {
"command": "bundle",
"args": ["exec", "ruby", "/path/to/your/server.rb"]
}
}
}Prompts to try
Once your Ruby MCP server is running and connected, test it with prompts matching your registered tools.
- "Greet Alice using the Ruby MCP server"
- "List all tools available from my Ruby server"
- "Call the greet tool with name set to Bob"
- "What resources does the Ruby MCP server expose?"
- "Use the Ruby server to run my custom data processing tool"Troubleshooting Ruby SDK
Server exits immediately with a LoadError or 'cannot load such file' error
Ensure the mcp gem is installed in the current bundle by running `bundle install` in your project directory. Check that your Gemfile includes `gem 'mcp'` and that you are running the server with `bundle exec ruby server.rb`.
MCP client shows 'server disconnected' or times out on startup
Stdio servers must not write anything to stdout before `transport.open` is called, as MCP clients parse stdout as JSON-RPC. Remove any `puts` or `p` debug statements that appear before the transport is opened.
HTTP transport returns 404 when mounted in Rails
Ensure the route is mounted before other catch-all routes in config/routes.rb. Restart the Rails server after updating routes and verify the mount path matches what your MCP client is configured to connect to.
Frequently Asked Questions about Ruby SDK
What is Ruby SDK?
Ruby SDK is a Model Context Protocol (MCP) server that [rust mcp sdk](https://github.com/modelcontextprotocol/rust-sdk) It connects AI assistants to external tools and data sources through a standardized interface.
How do I install Ruby SDK?
Follow the installation instructions on the Ruby SDK GitHub repository. Clone the repo, install dependencies, and add the server config to your AI client.
Which AI clients work with Ruby SDK?
Ruby SDK works with all major MCP-compatible AI clients including Claude Desktop, Claude Code, Cursor, VS Code (GitHub Copilot), Windsurf, and Cline.
Is Ruby SDK free to use?
Yes, Ruby SDK is open source and available under the NOASSERTION license. You can use it freely in both personal and commercial projects.
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