kotlin-sdk/samples/kotlin-mcp-server

MCP Kotlin Server Sample

A sample implementation of an MCP (Model Context Protocol) server in Kotlin that demonstrates different server configurations and transport methods.

Features

• Multiple server operation modes:
  • Standard I/O server
  • SSE (Server-Sent Events) server with plain configuration
  • SSE server using Ktor plugin
• Built-in capabilities for:
  • Prompts management
  • Resources handling
  • Tools integration

Getting Started

Running the Server

The server defaults STDIO transport.

You can customize the behavior using command-line arguments. Logs are printed to ./build/stdout.log

Standard I/O mode (STDIO):

./gradlew clean build

Use the MCP inspector to connect to MCP via STDIO (Click the "▶️ Connect" button):

npx @modelcontextprotocol/inspector --config mcp-inspector-config.json --server stdio-server

SSE with plain configuration:

NB!: 🐞 This configuration may not work ATM

./gradlew run --args="--sse-server 3001"

or

./gradlew clean build
java -jar ./build/libs/kotlin-mcp-server-0.1.0-all.jar --sse-server 3001

Use the MCP inspector to connect to http://localhost:3002/ via SSE Transport (Click the "▶️ Connect" button):

npx @modelcontextprotocol/inspector --config mcp-inspector-config.json --server sse-server

SSE with Ktor plugin:

./gradlew run --args="--sse-server-ktor 3002"

or

./gradlew clean build
java -jar ./build/libs/kotlin-mcp-server-0.1.0-all.jar --sse-server-ktor 3002

Use the MCP inspector to connect to http://localhost:3002/ via SSE transport (Click the "▶️ Connect" button):

npx @modelcontextprotocol/inspector --config mcp-inspector-config.json --server sse-ktor-server

Server Capabilities

• Prompts: Supports prompt management with list change notifications
• Resources: Includes subscription support and list change notifications
• Tools: Supports tool management with list change notifications

Implementation Details

The server is implemented using:

• Ktor for HTTP server functionality (SSE modes)
• Kotlin coroutines for asynchronous operations
• SSE for real-time communication in web contexts
• Standard I/O for command-line interface and process-based communication

Example Capabilities

The sample server demonstrates:

• Prompt: "Kotlin Developer" - helps develop small Kotlin applications with a configurable project name
• Tool: "kotlin-sdk-tool" - a simple test tool that returns a greeting
• Resource: "Web Search" - a placeholder resource demonstrating resource handling