mcpkit-client

Client implementation for the Model Context Protocol (MCP).

This crate provides the client-side implementation including a fluent client API, server discovery, and connection pooling.

Overview

The MCP client allows AI applications to:

• Connect to MCP servers via various transports
• Discover and invoke tools
• Read resources
• Get prompts
• Track long-running tasks
• Handle server-initiated requests (sampling, elicitation)

Usage

use mcpkit_client::ClientBuilder;
use mcpkit_transport::SpawnedTransport;

#[tokio::main]
async fn main() -> Result<(), mcpkit_core::error::McpError> {
    // Spawn an MCP server as a subprocess
    let transport = SpawnedTransport::spawn("my-mcp-server", &[] as &[&str]).await?;

    let client = ClientBuilder::new()
        .name("my-client")
        .version("1.0.0")
        .build(transport)
        .await?;

    // List available tools
    let tools = client.list_tools().await?;

    // Call a tool
    let result = client.call_tool("add", serde_json::json!({
        "a": 1,
        "b": 2
    })).await?;

    Ok(())
}

Features

Server Discovery

Discover MCP servers from configuration:

use mcpkit_client::ServerDiscovery;

let discovery = ServerDiscovery::new();
discovery.register("my-server", config);
let server = discovery.get("my-server");

Connection Pooling

Manage multiple client connections:

use mcpkit_client::{ClientPool, PoolConfig};

let pool = ClientPool::builder()
    .max_connections(10)
    .build();

Client Handler

Handle server-initiated requests by implementing ClientHandler:

use mcpkit_client::ClientHandler;

struct MyHandler;

impl ClientHandler for MyHandler {
    // Handle sampling requests, elicitation, etc.
}

Part of mcpkit

This crate is part of the mcpkit SDK. For most use cases, depend on mcpkit directly rather than this crate.

License

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