塔式MCP工具

Installation

Add to your Cargo.toml:

[dependencies]
tower-mcp = "0.9"

Builder Pattern (Recommended)

use tower_mcp::{ToolBuilder, CallToolResult};
use schemars::JsonSchema;
use serde::Deserialize;

#[derive(Debug, Deserialize, JsonSchema)]
struct AddInput {
    a: i64,
    b: i64,
}

let add = ToolBuilder::new("add")
    .description("Add two numbers")
    .read_only()  // Hint: this tool doesn't modify state
    .handler(|input: AddInput| async move {
        Ok(CallToolResult::text(format!("{}", input.a + input.b)))
    })
    .build();

Quick Start

use tower_mcp::{McpRouter, ToolBuilder, CallToolResult};
use schemars::JsonSchema;
use serde::Deserialize;

// Define your input type - schema is auto-generated
#[derive(Debug, Deserialize, JsonSchema)]
struct GreetInput {
    name: String,
}

// Build a tool with type-safe handler
let greet = ToolBuilder::new("greet")
    .title("Greet")
    .description("Greet someone by name")
    .handler(|input: GreetInput| async move {
        Ok(CallToolResult::text(format!("Hello, {}!", input.name)))
    })
    .build();

// Create router with tools
let router = McpRouter::new()
    .server_info("my-server", "1.0.0")
    .instructions("This server provides greeting functionality")
    .tool(greet);

// The router implements tower::Service and can be composed with middleware

Examples

A full-featured MCP server for querying crates.io is available as a standalone project: cratesio-mcp. A demo instance is deployed at https://cratesio-mcp.fly.dev -- connect with any MCP client that supports HTTP transport.

The repo includes 24 focused examples organized by topic:

Clone the repo and the .mcp.json configures example servers automatically:

```bash git clone https://github.com/joshrotenberg/tower-mcp cd tower-mcp

Proc Macros (Optional)

Enable with features = ["macros"]. The macros generate builder code -- you can always eject to the builder pattern for full control.

use tower_mcp::{tool_fn, prompt_fn, resource_fn, resource_template_fn};
use tower_mcp::{CallToolResult, McpRouter};
use tower_mcp::protocol::{GetPromptResult, ReadResourceResult};

#[derive(Debug, Deserialize, JsonSchema)]
struct AddInput { a: i64, b: i64 }

#[tool_fn(description = "Add two numbers")]
async fn add(input: AddInput) -> Result<CallToolResult, tower_mcp::Error> {
    Ok(CallToolResult::text(format!("{}", input.a + input.b)))
}

#[prompt_fn(description = "Greet someone", args(name = "Name to greet"))]
async fn greet(args: HashMap<String, String>) -> Result<GetPromptResult, tower_mcp::Error> {
    let name = args.get("name").cloned().unwrap_or_default();
    Ok(GetPromptResult::user_message(format!("Hello, {name}!")))
}

#[resource_fn(uri = "app://config", description = "App configuration")]
async fn config() -> Result<ReadResourceResult, tower_mcp::Error> {
    Ok(ReadResourceResult::text("app://config", "debug=true"))
}

// Each macro generates a constructor: add_tool(), greet_prompt(), config_resource()
let router = McpRouter::new()
    .server_info("my-server", "1.0.0")
    .tool(add_tool())
    .prompt(greet_prompt())
    .resource(config_resource());