Crate mcpkit_macros 

Procedural macros for the MCP SDK.

This crate provides the unified #[mcp_server] macro that simplifies MCP server development.

Overview

The macro system provides:

• #[mcp_server] - Transform an impl block into a full MCP server
• #[tool] - Mark a method as an MCP tool
• #[resource] - Mark a method as an MCP resource handler
• #[prompt] - Mark a method as an MCP prompt handler

Example

use mcpkit::prelude::*;
use mcpkit::transport::stdio::StdioTransport;

struct Calculator;

#[mcp_server(name = "calculator", version = "1.0.0")]
impl Calculator {
    /// Add two numbers together
    #[tool(description = "Add two numbers")]
    async fn add(&self, a: f64, b: f64) -> ToolOutput {
        ToolOutput::text((a + b).to_string())
    }

    /// Multiply two numbers
    #[tool(description = "Multiply two numbers")]
    async fn multiply(&self, a: f64, b: f64) -> ToolOutput {
        ToolOutput::text((a * b).to_string())
    }
}

#[tokio::main]
async fn main() -> Result<(), McpError> {
    let transport = StdioTransport::new();
    let server = ServerBuilder::new(Calculator)
        .with_tools(Calculator)
        .build();
    server.serve(transport).await
}

Code Reduction

This single macro replaces 4 separate macros:

• #[derive(Clone)] with manual router field
• #[tool_router]
• #[tool_handler]
• Manual new() constructor

Result: Reduced boilerplate code.

Attribute Macros

elicitation

Mark a method as an elicitation handler.

mcp_client

The unified MCP client macro.

mcp_server

The unified MCP server macro.

on_connected

Mark a method as the connection established handler.

on_disconnected

Mark a method as the disconnection handler.

on_prompts_list_changed

Mark a method as a prompts list change notification handler.

on_resource_updated

Mark a method as a resource update notification handler.

on_resources_list_changed

Mark a method as a resources list change notification handler.

on_task_progress

Mark a method as a task progress notification handler.

on_tools_list_changed

Mark a method as a tools list change notification handler.

prompt

Mark a method as an MCP prompt handler.

resource

Mark a method as an MCP resource handler.

roots

Mark a method as a roots handler.

sampling

Mark a method as a sampling handler.

tool

Mark a method as an MCP tool.

Derive Macros

ToolInput

Derive macro for tool input types.