This repository is moved

The new repo is located here: https://github.com/modelcontextprotocol/kotlin-sdk

MCP Kotlin SDK

Kotlin implementation of the Model Context Protocol (MCP), providing both client and server capabilities for integrating with LLM surfaces.

Overview

The Model Context Protocol allows applications to provide context for LLMs in a standardized way, separating the concerns of providing context from the actual LLM interaction. This Kotlin SDK implements the full MCP specification, making it easy to:

• Build MCP clients that can connect to any MCP server
• Create MCP servers that expose resources, prompts and tools
• Use standard transports like stdio, SSE, and WebSocket
• Handle all MCP protocol messages and lifecycle events

Samples

• kotlin-mcp-server: shows how to set up Kotlin MCP server with different tools and other features.

Installation

Add the new repository to your build file:

repositories {
    maven(url = "https://maven.pkg.jetbrains.space/public/p/kotlin-mcp-sdk/sdk")
}

Add the dependency:

dependencies {
    implementation("org.jetbrains.kotlinx:kotlinx-mcp-sdk:0.1.0")
}

Quick Start

Creating a Client

import org.jetbrains.kotlinx.mcp.client.Client
import org.jetbrains.kotlinx.mcp.client.StdioClientTransport
import org.jetbrains.kotlinx.mcp.Implementation

val client = Client(
    clientInfo = Implementation(
        name = "example-client",
        version = "1.0.0"
    )
)

val transport = StdioClientTransport(
    inputStream = processInputStream,
    outputStream = processOutputStream
)

// Connect to server
client.connect(transport)

// List available resources
val resources = client.listResources()

// Read a specific resource
val resourceContent = client.readResource(
    ReadResourceRequest(uri = "file:///example.txt")
)

Creating a Server

import org.jetbrains.kotlinx.mcp.server.Server
import org.jetbrains.kotlinx.mcp.server.ServerOptions
import org.jetbrains.kotlinx.mcp.server.StdioServerTransport
import org.jetbrains.kotlinx.mcp.ServerCapabilities

val server = Server(
    serverInfo = Implementation(
        name = "example-server",
        version = "1.0.0"
    ),
    options = ServerOptions(
        capabilities = ServerCapabilities(
            resources = ServerCapabilities.Resources(
                subscribe = true,
                listChanged = true
            )
        )
    )
)

// Add a resource
server.addResource(
    uri = "file:///example.txt",
    name = "Example Resource",
    description = "An example text file",
    mimeType = "text/plain"
) { request ->
    ReadResourceResult(
        contents = listOf(
            TextResourceContents(
                text = "This is the content of the example resource.",
                uri = request.uri,
                mimeType = "text/plain"
            )
        )
    )
}

// Start server with stdio transport
val transport = StdioServerTransport()
server.connect(transport)

Using SSE Transport

import io.ktor.server.application.*
import org.jetbrains.kotlinx.mcp.server.MCP

fun Application.module() {
    MCP {
        Server(
            serverInfo = Implementation(
                name = "example-sse-server",
                version = "1.0.0"
            ),
            options = ServerOptions(
                capabilities = ServerCapabilities(
                    prompts = ServerCapabilities.Prompts(listChanged = null),
                    resources = ServerCapabilities.Resources(subscribe = null, listChanged = null)
                )
            )
        )
    }
}

Contributing

Please see the contribution guide and the Code of conduct before contributing.

License

This project is licensed under the MIT License—see the LICENSE file for details.