Rust MCP Server with ContextVM

A sample Rust MCP (Model Context Protocol) server that adds two numbers together, exposed via ContextVM gateway over Nostr.

Structure

This workspace contains two crates:

1. adder-cli - A simple CLI that adds two numbers
2. adder-mcp - An MCP server that exposes an add tool

Prerequisites

• Rust (with cargo)
• ContextVM Gateway CLI

Installation

1. Build the project

cargo build --release

2. Install Gateway CLI

curl -fsSL https://raw.githubusercontent.com/contextvm/gateway-cli/main/install.sh | bash

Or download the binary for your platform from the releases page.

3. Configure the gateway

Copy the example config and add your Nostr private key:

cp example.contextgw.config.yml contextgw.config.yml

Edit contextgw.config.yml and replace YOUR_NOSTR_PRIVATE_KEY_HEX_HERE with your Nostr private key in hex format.

If you have an nsec key, you can convert it to hex using a tool like nostr-tool or online converters.

Usage

Running the CLI directly

./target/release/adder-cli 5 3
# Output: 8

Running the MCP server via ContextVM Gateway

gateway

This will:

• Start your MCP server (adder-mcp)
• Connect to the ContextVM Nostr relay
• Make it publicly discoverable
• Use NIP-44 encryption for secure communication

The gateway will display the server's public key (npub) that clients can use to connect.

MCP Tools

The server exposes one tool:

• add - Adds two numbers together
  • Parameters:
    • a (float): The first number
    • b (float): The second number
  • Returns: The sum as a string

Connecting to the Server

Once running, clients can connect to your MCP server using:

• The npub/public key displayed by the gateway
• Any MCP client that supports ContextVM/Nostr transport

License

MIT