wasmcp Rust SDK

SDK for building MCP (Model Context Protocol) handler components in Rust.

Installation

Add to your Cargo.toml:

[dependencies]
wasmcp = "0.0.1"

Usage

This SDK provides types and a macro to help you implement MCP handlers. Here's how to create a component:

1. Create a new component project

cargo component new my-mcp-handler --lib
cd my-mcp-handler

2. Add the MCP WIT files

Copy the WIT files from the wasmcp repository to your project's wit directory, or reference them in your Cargo.toml:

[package.metadata.component.target.dependencies]
"wasmcp:mcp" = { path = "../path/to/wasmcp/wit" }

3. Implement your handler

use wasmcp::{create_handler, json, Tool, Resource, Prompt};

fn get_tools() -> Vec<Tool> {
    vec![
        wasmcp::create_tool(
            "hello",
            "Says hello",
            json!({
                "type": "object",
                "properties": {
                    "name": { "type": "string" }
                }
            }),
            |args| {
                let name = args["name"].as_str().unwrap_or("World");
                Ok(format!("Hello, {}!", name))
            }
        )
    ]
}

fn get_resources() -> Vec<Resource> {
    vec![]
}

fn get_prompts() -> Vec<Prompt> {
    vec![]
}

create_handler!(
    tools: get_tools,
    resources: get_resources,
    prompts: get_prompts
);

4. Build your component

cargo component build --release

Features

The SDK provides:

• Tool, Resource, and Prompt types
• Builder functions: create_tool(), create_resource(), create_prompt()
• The create_handler! macro to generate component bindings
• Convenience macros: tool!, resource!, prompt!

Example

See the examples directory for complete working examples.