MCP Macros

Procedural macros for the Model Context Protocol (MCP) Rust implementation.

Features

This crate provides procedural macros to reduce boilerplate when defining MCP servers:

• #[mcp_server] - Define server metadata and collect tools
• #[mcp_tool] - Mark a method as an MCP tool
• #[mcp_internal] - Mark a server as built-in (no stdio wrapper)

Usage

use mcp::macros::{mcp_server, mcp_tool};
use mcp::ToolResult;
use serde_json::Value;

#[mcp_server(name = "calculator", version = "1.0.0")]
pub struct CalculatorServer;

#[mcp_server]
impl CalculatorServer {
    #[mcp_tool(description = "Add two numbers")]
    pub fn add(&self, a: f64, b: f64) -> ToolResult<f64> {
        Ok(a + b)
    }
    
    #[mcp_tool(description = "Multiply two numbers")]
    pub fn multiply(&self, a: f64, b: f64) -> ToolResult<f64> {
        Ok(a * b)
    }
}

Parameter Documentation

Tool parameters can be documented using doc comments:

#[mcp_tool(description = "Store a value in memory")]
pub fn memory_write(
    &self,
    /// The scope/namespace for the memory
    scope: String,
    /// The key to store the value under
    key: String,
    /// The value to store (can be any JSON value)
    value: Value,
) -> ToolResult<String> {
    // implementation
}

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.