modelcontextprotocol/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:
kotlin
repositories {
mavenCentral()
dependencies {
// See the badge above for the latest version
implementation("io.modelcontextprotocol:kotlin-sdk:$mcpVersion")
Use kotlin-sdk-client or kotlin-sdk-server if you only need one side of the API:
kotlin
dependencies {
implementation("io.modelcontextprotocol:kotlin-sdk-client:$mcpVersion")
implementation("io.modelcontextprotocol:kotlin-sdk-server:$mcpVersion")
### Multiplatform
In a Kotlin Multiplatform project you can add the SDK to commonMain:
kotlin
commonMain {
dependencies {
// Works as a common dependency as well as the platform one
implementation("io.modelcontextprotocol:kotlin-sdk:$mcpVersion")
### Ktor dependencies
The Kotlin MCP SDK uses Ktor, but it does not add Ktor engine dependencies transitively.
You need to declare
Ktor client/server
dependencies yourself (or reuse the ones already used in your project),
for example:
kotlin
dependencies {
// MCP client with Ktor
implementation("io.ktor:ktor-client-cio:$ktorVersion")
implementation("io.modelcontextprotocol:kotlin-sdk-client:$mcpVersion")
// MCP server with Ktor
implementation("io.ktor:ktor-server-netty:$ktorVersion")
implementation("io.modelcontextprotocol:kotlin-sdk-server:$mcpVersion")
## Quickstart
Let's create a simple MCP client and server to demonstrate the basic usage of the Kotlin SDK.
### Creating a Client
Create an MCP client that connects to a server via Streamable HTTP transport and lists available tools:
kotlin
import io.ktor.client.HttpClient
import io.ktor.client.plugins.sse.SSE
import io.modelcontextprotocol.kotlin.sdk.client.Client
import io.modelcontextprotocol.kotlin.sdk.client.StreamableHttpClientTransport