Offeryn Rust MCP

[dependencies]
offeryn = { git = "https://github.com/avahowell/offeryn" }
tokio = { version = "1", features = ["full"] }

use offeryn::mcp_tool;

#[mcp_tool]
struct Calculator;

#[mcp_tool]
impl Calculator {
    /// Add two numbers
    fn add(&self, a: f64, b: f64) -> f64 {
        a + b
    }

    /// Divide two numbers
    fn divide(&self, a: f64, b: f64) -> Result<f64, String> {
        if b == 0.0 { Err("Division by zero".to_string()) }
        else { Ok(a / b) }
    }
}

use offeryn::{McpServer, StdioTransport};

#[tokio::main]
async fn main() {
    let mut server = McpServer::new("my-server", "1.0.0");
    server.register_tools(Calculator);
    let transport = StdioTransport::new();
    server.run(transport).await.unwrap();
}

cargo build --release

{
  "mcpServers": {
    "my-rust-server": {
      "command": "/path/to/your/project/target/release/my-server"
    }
  }
}

use offeryn::{McpServer, SseTransport};
use tokio::net::TcpListener;

#[tokio::main]
async fn main() {
    let mut server = McpServer::new("my-server", "1.0.0");
    server.register_tools(Calculator);
    let router = SseTransport::create_router(&server);
    let listener = TcpListener::bind("127.0.0.1:3000").await.unwrap();
    axum::serve(listener, router).await.unwrap();
}