rust_mcp 0.1.0

use rust_mcp::McpServer;
use serde_json::json;
use std::error::Error;

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    // create a new mcp server
    let mut server = McpServer::new("rust-calculator", "0.1.0");
    
    // register the calculate tool
    server.add_tool(
        "calculate",
        "Perform basic arithmetic operations",
        json!({
            "type": "object",
            "properties": {
                "operation": {
                    "type": "string", 
                    "description": "One of: add, subtract, multiply, divide"
                },
                "a": { "type": "number" },
                "b": { "type": "number" }
            },
            "required": ["operation", "a", "b"]
        }),
        |args| async move {
            // Parse arguments
            let operation = match args.get("operation") {
                Some(serde_json::Value::String(op)) => op.as_str(),
                _ => return Err("Missing or invalid operation".into()),
            };
            
            let a = match args.get("a") {
                Some(serde_json::Value::Number(n)) => n.as_f64().unwrap_or(0.0),
                _ => return Err("Missing or invalid first number".into()),
            };
            
            let b = match args.get("b") {
                Some(serde_json::Value::Number(n)) => n.as_f64().unwrap_or(0.0),
                _ => return Err("Missing or invalid second number".into()),
            };
            
            // Perform calculation
            let result = match operation {
                "add" => a + b,
                "subtract" => a - b,
                "multiply" => a * b,
                "divide" => {
                    if b == 0.0 {
                        return Err("Division by zero".into());
                    }
                    a / b
                }
                _ => return Err(format!("Unknown operation: {}", operation)),
            };
            
            Ok(json!(result))
        },
    );
    
    // start the server
    server.run_stdio().await?;
    
    Ok(())
}