Elixir MCP Server
About
An example of how to implement an MCP server using Elixir and SSE transport
Details
- License
- MIT license
Explore
- Implements the Model Context Protocol (MCP) using SSE transport
- Built with Elixir, Bandit, and Plug
- Provides three built-in tools: list_files, echo, get_weather
- Supports custom tools by modifying handle_initialize and handle_call_tool
- Can be tested with the NXP Inspector client
- Elixir 1.18 or higher
- Erlang/OTP 27 or higher
- The weather API key can be set through the WEATHER_API_KEY environment variable.
The default service is using the free tier of https://www.weatherapi.com/.
list_files
List files in a directory
echo
Echo a message back
get_weather
Get weather information
- list_files: List files in a directory
- echo: Echo a message back
- get_weather: Get weather information
An Elixir implementation of the Model Context Protocol (MCP) server using Elixir with Bandit and Plug.
The Model Context Protocol (MCP) is an open protocol that enables AI models to securely interact with local and remote resources through standardized server implementations.
This project is a basic example of an MCP server using SSE (Server-Sent Events) as the transport protocol. It is based off the example at https://modelcontextprotocol.io/quickstart/server
Prerequisites
- Elixir 1.18 or higher
- Erlang/OTP 27 or higher
- The weather API key can be set through the WEATHER_API_KEY environment variable.
The default service is using the free tier of https://www.weatherapi.com/.
Getting Started
1. Install dependencies:
mix deps.get
2. Start the server:
``
WEATHER_API_KEY="1234567890abcdef" mix run --no-halt
3. The server will be available at:
- SSE endpoint: http://localhost:4000/sse
- Message endpoint: http://localhost:4000/message
Available Tools
- list_files: List files in a directoryecho
- : Echo a message backget_weather
- : Get weather information
Testing with MCP Client
Install the NXP Inspector client and follow the instructions to connect to the server.
Make sure to use SSE (Server-Sent Events) as the transport protocol, then you should be able to list available tools and call them. Also to ping/keepalive the connection, you can use the ping tool.
Adding Custom Tools
To add custom tools, update the handle_initialize/2 function to include your tool definitions and implement corresponding handle_call_tool/3` clauses.
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