MCP Ruby Server Skeleton

What is MCP Ruby Server Skeleton?

The MCP Ruby Server Skeleton is a Ruby implementation of a Model Context Protocol (MCP) server that provides an interface for Large Language Models (LLMs) like Claude to call tools. It is designed for developers who want to build custom MCP servers in Ruby, starting with a built‑in tool that generates random numbers.

How to use MCP Ruby Server Skeleton?

Clone the repository, make the server script executable (chmod +x bin/run_server.rb), then run it directly with ./bin/run_server.rb or integrate it with Claude Desktop by adding a configuration entry to claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/claude_desktop_config.json, Windows: %APPDATA%\Claude\claude_desktop_config.json). After restarting Claude Desktop, you can prompt it to generate a random number.

Key features of MCP Ruby Server Skeleton

• Built‑in get-random-number tool (generates random integer between 1 and a specified max)
• MCP protocol version 2024‑11‑05 compatibility
• JSON‑RPC 2.0 compliant message handling
• Detailed logging via STDERR for debugging
• Standard I/O transport layer for communication
• Extensible architecture for adding custom tools

Use cases of MCP Ruby Server Skeleton

• Provide LLMs with a random number generation tool
• Serve as a starting template for building custom MCP servers in Ruby
• Integrate with Claude Desktop to extend its capabilities
• Test and prototype MCP protocol interactions in Ruby

FAQ from MCP Ruby Server Skeleton

What alternatives exist?

This is a Ruby‑specific MCP server skeleton; similar implementations exist in other languages (e.g., TypeScript). The README is inspired by a TypeScript MCP server article.

What are the runtime requirements?

Ruby 3.0 or later is required.

Where does the server data live?

The server communicates via STDIN/STDOUT and logs to STDERR. Claude Desktop logs are stored locally (macOS: ~/Library/Logs/Claude/mcp*.log, Windows: %APPDATA%\Claude\logs\mcp*.log).

What are the known limitations or common issues?

Server disconnection may occur due to protocol version mismatch, malformed JSON‑RPC messages, improper initialization, or missing file permissions. If the tool does not appear in Claude, check the server registration, script execution permissions, and restart the client.

What transport and authentication are used?

The server uses Standard I/O transport (Stdio) for communication. Authentication is not mentioned in the README; the server is designed for local use with Claude Desktop.