kotlin-sdk

# MCP Kotlin SDK [](https://central.sonatype.com/artifact/io.modelcontextprotocol/kotlin-sdk) [](https://github.com/modelcontextprotocol/kotlin-sdk/actions/workflows/build.yml) [](http://kotlinlang.org) [](https://kotlinlang.org/docs/multiplatform.html) [](http://java.com) [](LICENSE) Kotlin Multiplatform implementation of the [Model Context Protocol](https://modelcontextprotocol.io) (MCP), providing both client and server capabilities for integrating with LLM surfaces across various platforms. ## 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 SDK implements the MCP specification for Kotlin, enabling you to build applications that can communicate using MCP on the JVM, WebAssembly and iOS. - 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](./samples/kotlin-mcp-server): demonstrates a multiplatform (JVM, Wasm) MCP server setup with various features and transports. - [weather-stdio-server](./samples/weather-stdio-server): shows how to build a Kotlin MCP server providing weather forecast and alerts using STDIO transport. - [kotlin-mcp-client](./samples/kotlin-mcp-client): demonstrates building an interactive Kotlin MCP client that connects to an MCP server via STDIO and integrates with Anthropic’s API. ## Installation Add the new repository to your build file: ```kotlin repositories { mavenCentral() } ``` Add the dependency: ```kotlin dependencies { // See the badge above for the latest version implementation("io.modelcontextprotocol:kotlin-sdk:$mcpVersion") } ``` MCP SDK uses [Ktor](https://ktor.io/), but does not come with a specific engine dependency. You should add [Ktor client](https://ktor.io/docs/client-dependencies.html#engine-dependency) and/or [Ktor server](https://ktor.io/docs/client-dependencies.html#engine-dependency) dependency to your project yourself, e.g.: ```kotlin dependencies { // for client: implementation("io.ktor:ktor-client-cio:$ktorVersion") // for server: implementation("io.ktor:ktor-server-netty:$ktorVersion") } ``` ## Quick Start ### Creating a Client ```kotlin import io.modelcontextprotocol.kotlin.sdk.client.Client import io.modelcontextprotocol.kotlin.sdk.client.StdioClientTransport import io.modelcontextprotocol.kotlin.sdk.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 ```kotlin import io.modelcontextprotocol.kotlin.sdk.server.Server import io.modelcontextprotocol.kotlin.sdk.server.ServerOptions import io.modelcontextprotocol.kotlin.sdk.server.StdioServerTransport import io.modelcontextprotocol.kotlin.sdk.ServerCapabilities val server = Server( serverInfo = Implementation( name = "example-server", version = "1.0.0" ), options = ServerOptions( capabilities = ServerCapabilities( resources = ServerCapabilities.Resources( subscribe = true, listChanged = true ) ) ) ){ "This server provides example resources and demonstrates MCP capabilities." } // 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 Directly in Ktor's `Application`: ```kotlin i