Elixir MCP Server

🚀 Elixir MCP Server

An implementation of the Model Context Protocol (MCP) server in Elixir, based on Bandit and Plug.

The Model Context Protocol (MCP) is an open protocol that allows AI models to securely interact with local and remote resources through a standardized server. This project is a basic example of an MCP server using Server-Sent Events (SSE) as the transport protocol. It is based on the following example: https://modelcontextprotocol.io/quickstart/server

🚀 Quick Start

Prerequisites

• Elixir 1.18 or higher
• Erlang/OTP 27 or higher
• A weather API key, which can be set via the WEATHER_API_KEY environment variable. The default service uses the free tier of https://www.weatherapi.com/.

Steps

1. Install dependencies:

mix deps.get

2. Start the server:

WEATHER_API_KEY="1234567890abcdef" mix run --no-halt

3. The server will run on the following endpoints:

• SSE endpoint: http://localhost:4000/sse
• Message endpoint: http://localhost:4000/message

✨ Features

Available Tools

• list_files: List files in a directory
• echo: Echo a message
• get_weather: Get weather information

Testing with an MCP Client

Install the NXP Inspector client and follow the instructions to connect to the server.

Ensure that you use Server-Sent Events (SSE) as the transport protocol. Then you should be able to list the available tools and call them. Additionally, you can use the ping tool to keep the connection alive.

Adding Custom Tools

To add custom tools, update the handle_initialize/2 function to include your tool definitions and implement the corresponding handle_call_tool/3 clauses.