kotlin-mcp-server-generator

SKILL.md

Kotlin MCP Server Project Generator

Generate a complete, production-ready Model Context Protocol (MCP) server project in Kotlin.

Project Requirements

You will create a Kotlin MCP server with:

Project Structure: Gradle-based Kotlin project layout

Dependencies: Official MCP SDK, Ktor, and kotlinx libraries

Server Setup: Configured MCP server with transports

Tools: At least 2-3 useful tools with typed inputs/outputs

Error Handling: Proper exception handling and validation

Documentation: README with setup and usage instructions

Testing: Basic test structure with coroutines

Template Structure
myserver/
├── build.gradle.kts
├── settings.gradle.kts
├── gradle.properties
├── src/
│   ├── main/
│   │   └── kotlin/
│   │       └── com/example/myserver/
│   │           ├── Main.kt
│   │           ├── Server.kt
│   │           ├── config/
│   │           │   └── Config.kt
│   │           └── tools/
│   │               ├── Tool1.kt
│   │               └── Tool2.kt
│   └── test/
│       └── kotlin/
│           └── com/example/myserver/
│               └── ServerTest.kt
└── README.md

build.gradle.kts Template

plugins {
    kotlin("jvm") version "2.1.0"
    kotlin("plugin.serialization") version "2.1.0"
    application
}

group = "com.example"
version = "1.0.0"

repositories {
    mavenCentral()
}

dependencies {
    implementation("io.modelcontextprotocol:kotlin-sdk:0.7.2")
    
    // Ktor for transports
    implementation("io.ktor:ktor-server-netty:3.0.0")
    implementation("io.ktor:ktor-client-cio:3.0.0")
    
    // Serialization
    implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.7.3")
    
    // Coroutines
    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.9.0")
    
    // Logging
    implementation("io.github.oshai:kotlin-logging-jvm:7.0.0")
    implementation("ch.qos.logback:logback-classic:1.5.12")
    
    // Testing
    testImplementation(kotlin("test"))
    testImplementation("org.jetbrains.kotlinx:kotlinx-coroutines-test:1.9.0")
}

application {
    mainClass.set("com.example.myserver.MainKt")
}

tasks.test {
    useJUnitPlatform()
}

kotlin {
    jvmToolchain(17)
}

settings.gradle.kts Template

rootProject.name = "{{PROJECT_NAME}}"

Main.kt Template

package com.example.myserver

import io.modelcontextprotocol.kotlin.sdk.server.StdioServerTransport
import kotlinx.coroutines.runBlocking
import io.github.oshai.kotlinlogging.KotlinLogging

private val logger = KotlinLogging.logger {}

fun main() = runBlocking {
    logger.info { "Starting MCP server..." }
    
    val config = loadConfig()
    val server = createServer(config)
    
    // Use stdio transport
    val transport = StdioServerTransport()
    
    logger.info { "Server '${config.name}' v${config.version} ready" }
    server.connect(transport)
}

Server.kt Template

package com.example.myserver

import io.modelcontextprotocol.kotlin.sdk.server.Server
import io.modelcontextprotocol.kotlin.sdk.server.ServerOptions
import io.modelcontextprotocol.kotlin.sdk.Implementation
import io.modelcontextprotocol.kotlin.sdk.ServerCapabilities
import com.example.myserver.tools.registerTools

fun createServer(config: Config): Server {
    val server = Server(
        serverInfo = Implementation(
            name = config.name,
            version = config.version
        ),
        options = ServerOptions(
            capabilities = ServerCapabilities(
                tools = ServerCapabilities.Tools(),
                resources = ServerCapabilities.Resources(
                    subscribe = true,
                    listChanged = true
                ),
                prompts = ServerCapabilities.Prompts(listChanged = true)
            )
        )
    ) {
        config.description
    }
    
    // Register all tools
    server.registerTools()
    
    return server
}

Config.kt Template

package com.example.myserver.config

import kotlinx.serialization.Serializable

@Serializable
data class Config(
    val name: String = "{{PROJECT_NAME}}",
    val version: String = "1.0.0",
    val description: String = "{{PROJECT_DESCRIPTION}}"
)

fun loadConfig(): Config {
    return Config(
        name = System.getenv("SERVER_NAME") ?: "{{PROJECT_NAME}}",
        version = System.getenv("VERSION") ?: "1.0.0",
        description = System.getenv("DESCRIPTION") ?: "{{PROJECT_DESCRIPTION}}"
    )
}

Tool1.kt Template

package com.example.myserver.tools

import io.modelcontextprotocol.kotlin.sdk.server.Server
import io.modelcontextprotocol.kotlin.sdk.CallToolRequest
import io.modelcontextprotocol.kotlin.sdk.CallToolResult
import io.modelcontextprotocol.kotlin.sdk.TextContent
import kotlinx.serialization.json.buildJsonObject
import kotlinx.serialization.json.put
import kotlinx.serialization.json.putJsonObject
import kotlinx.serialization.json.putJsonArray

fun Server.registerTool1() {
    addTool(
        name = "tool1",
        description = "Description of what tool1 does",
        inputSchema = buildJsonObject {
            put("type", "object")
            putJsonObject("properties") {
                putJsonObject("param1") {
                    put("type", "string")
                    put("description", "First parameter")
                }
                putJsonObject("param2") {
                    put("type", "integer")
                    put("description", "Optional second parameter")
                }
            }
            putJsonArray("required") {
                add("param1")
            }
        }
    ) { request: CallToolRequest ->
        // Extract and validate parameters
        val param1 = request.params.arguments["param1"] as? String
            ?: throw IllegalArgumentException("param1 is required")
        val param2 = (request.params.arguments["param2"] as? Number)?.toInt() ?: 0
        
        // Perform tool logic
        val result = performTool1Logic(param1, param2)
        
        CallToolResult(
            content = listOf(
                TextContent(text = result)
            )
        )
    }
}

private fun performTool1Logic(param1: String, param2: Int): String {
    // Implement tool logic here
    return "Processed: $param1 with value $param2"
}

tools/ToolRegistry.kt Template

package com.example.myserver.tools

import io.modelcontextprotocol.kotlin.sdk.server.Server

fun Server.registerTools() {
    registerTool1()
    registerTool2()
    // Register additional tools here
}

ServerTest.kt Template

package com.example.myserver

import kotlinx.coroutines.test.runTest
import kotlin.test.Test
import kotlin.test.assertEquals
import kotlin.test.assertFalse

class ServerTest {
    
    @Test
    fun `test server creation`() = runTest {
        val config = Config(
            name = "test-server",
            version = "1.0.0",
            description = "Test server"
        )
        
        val server = createServer(config)
        
        assertEquals("test-server", server.serverInfo.name)
        assertEquals("1.0.0", server.serverInfo.version)
    }
    
    @Test
    fun `test tool1 execution`() = runTest {
        val config = Config()
        val server = createServer(config)
        
        // Test tool execution
        // Note: You'll need to implement proper testing utilities
        // for calling tools in the server
    }
}

README.md Template

# {{PROJECT_NAME}}

A Model Context Protocol (MCP) server built with Kotlin.

## Description

{{PROJECT_DESCRIPTION}}

## Requirements

- Java 17 or higher
- Kotlin 2.1.0

## Installation

Build the project:

\`\`\`bash
./gradlew build
\`\`\`

## Usage

Run the server with stdio transport:

\`\`\`bash
./gradlew run
\`\`\`

Or build and run the jar:

\`\`\`bash
./gradlew installDist
./build/install/{{PROJECT_NAME}}/bin/{{PROJECT_NAME}}
\`\`\`

## Configuration

Configure via environment variables:

- `SERVER_NAME`: Server name (default: "{{PROJECT_NAME}}")
- `VERSION`: Server version (default: "1.0.0")
- `DESCRIPTION`: Server description

## Available Tools

### tool1
{{TOOL1_DESCRIPTION}}

**Input:**
- `param1` (string, required): First parameter
- `param2` (integer, optional): Second parameter

**Output:**
- Text result of the operation

## Development

Run tests:

\`\`\`bash
./gradlew test
\`\`\`

Build:

\`\`\`bash
./gradlew build
\`\`\`

Run with auto-reload (development):

\`\`\`bash
./gradlew run --continuous
\`\`\`

## Multiplatform

This project uses Kotlin Multiplatform and can target JVM, Wasm, and iOS.
See `build.gradle.kts` for platform configuration.

## License

MIT

Generation Instructions

When generating a Kotlin MCP server:

Gradle Setup: Create proper build.gradle.kts with all dependencies

Package Structure: Follow Kotlin package conventions

Type Safety: Use data classes and kotlinx.serialization

Coroutines: All operations should be suspending functions

Error Handling: Use Kotlin exceptions and validation

JSON Schemas: Use buildJsonObject for tool schemas

Testing: Include coroutine test utilities

Logging: Use kotlin-logging for structured logging

Configuration: Use data classes and environment variables

Documentation: KDoc comments for public APIs

Best Practices

Use suspending functions for all async operations

Leverage Kotlin's null safety and type system

Use data classes for structured data

Apply kotlinx.serialization for JSON handling

Use sealed classes for result types

Implement proper error handling with Result/Either patterns

Write tests using kotlinx-coroutines-test

Use dependency injection for testability

Follow Kotlin coding conventions

Use meaningful names and KDoc comments

Transport Options

Stdio Transport

val transport = StdioServerTransport()
server.connect(transport)

SSE Transport (Ktor)

embeddedServer(Netty, port = 8080) {
    mcp {
        Server(/*...*/) { "Description" }
    }
}.start(wait = true)

Multiplatform Configuration

For multiplatform projects, add to build.gradle.kts:

kotlin {
    jvm()
    js(IR) { nodejs() }
    wasmJs()
    
    sourceSets {
        commonMain.dependencies {
            implementation("io.modelcontextprotocol:kotlin-sdk:0.7.2")
        }
    }
}