MCP Kotlin SDK

Kotlin Multiplatform SDK for the Model Context Protocol. It enables Kotlin applications targeting JVM, Native, JS, and Wasm to implement MCP clients and servers using a standardized protocol interface.

Table of Contents

• Overview
• Installation
  • Artifacts
  • Gradle setup (JVM)
  • Multiplatform
  • Ktor dependencies
• Quickstart
  • Creating a Client
  • Creating a Server
• Core Concepts
  • MCP Primitives
  • Capabilities
    • Server Capabilities
    • Client Capabilities
  • Server Features
    • Prompts
    • Resources
    • Tools
    • Completion
    • Logging
    • Pagination
  • Client Features
    • Roots
    • Sampling
• Transports
  • STDIO Transport
  • Streamable HTTP Transport
  • SSE Transport
  • WebSocket Transport
  • ChannelTransport (testing)
• Connecting your server
• Examples
• Documentation
• Contributing
• License

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 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
• Target JVM, Native, JS, and Wasm from a single codebase
• Use standard transports like stdio, SSE, Streamable HTTP, and WebSocket
• Handle MCP protocol messages and lifecycle events with coroutine-friendly APIs

Installation

Artifacts

• io.modelcontextprotocol:kotlin-sdk – umbrella SDK (client + server APIs)
• io.modelcontextprotocol:kotlin-sdk-client – client-only APIs
• io.modelcontextprotocol:kotlin-sdk-server – server-only APIs

Gradle setup (JVM)

Add the Maven Central repository and the SDK dependency:

repositories {
    mavenCentral()
}

dependencies {
    // See the badge above for the latest version
    implementation("io.modelcontextprotocol:kotlin-sdk:$mcpVersion")
}

Use kotlin-sdk-client or kotlin-sdk-server if you only need one side of the API:

dependencies {
    implementation("io.modelcontextprotocol:kotlin-sdk-client:$mcpVersion")
    implementation("io.modelcontextprotocol:kotlin-sdk-server:$mcpVersion")
}

Multiplatform

In a Kotlin Multiplatform project you can add the SDK to commonMain:

commonMain {
    dependencies {
        // Works as a common dependency as well as the platform one
        implementation("io.modelcontextprotocol:kotlin-sdk:$mcpVersion")
    }
}

Ktor dependencies