hello mcp server / published by https://github.com/dacr/code-examples-manager #dccd5b3c-b53d-4c0b-8f91-b9889c3203f7/ce8973fc0526fc5a09bfc991eb163f248c375d3c

fastmcp-dummy-mcp-server.sc

// summary : hello mcp server
// keywords : artificial-intelligence, generative-ai, llm, ai, mcp, mcp-server, @testable
// publish : gist
// authors : David Crosson
// license : Apache License Version 2.0 (https://www.apache.org/licenses/LICENSE-2.0.txt)
// id : dccd5b3c-b53d-4c0b-8f91-b9889c3203f7
// created-on : 2025-07-01T14:23:09+02:00
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : scala-cli $file

//> using scala 3.7.1
//> using dep org.slf4j:slf4j-api:2.0.17
//> using dep org.slf4j:slf4j-simple:2.0.17
//> using dep com.tjclp::fast-mcp-scala:0.1.1
//> using dep fr.janalyse::lorem-ipsum:1.0.7

//> using options "-Xcheck-macros" "-experimental"

/*
{
  "mcpServers": {
    "hello-fast-mcp-server": {
      "command": "scala-cli",
      "args": [
        "hello-mcp-server.sc",
        "--offline",
        "--quiet"
      ]
    }
  }
}
 */

/*
{"jsonrpc":"2.0","id":0,"method":"initialize","params":{"protocolVersion": "2024-11-05"}}
{"jsonrpc":"2.0","id":1,"method":"tools/list","params":{}}
{"jsonrpc":"2.0","id":2,"method":"resources/list","params":{}}
{"jsonrpc":"2.0","id":3,"method":"prompts/list","params":{}}
{"jsonrpc":"2.0","id":4,"method":"tools/call","params":{"name":"add","arguments":{"a":40,"b": 2}}}
{"jsonrpc":"2.0","id":5,"method":"prompts/greet","params":{"Name to greet":"joe"}}
{"jsonrpc":"2.0","id":6,"method":"prompts/loremipsum","params":{}}

{"jsonrpc":"2.0","id":0,"method":"initialize","params":{"protocolVersion": "2024-11-05"}}
{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"hello"}}


{"jsonrpc":"2.0","id":0,"method":"initialize","params":{"protocolVersion": "2024-11-05"}}
{"jsonrpc":"2.0","id":1,"method":"prompts/get","params":{"name":"loremipsum"}}

 */

import com.tjclp.fastmcp.core.*
import com.tjclp.fastmcp.macros.RegistrationMacro.*
import com.tjclp.fastmcp.server.{FastMcpServer, FastMcpServerSettings}
import zio.*

// Define annotated tools, prompts, and resources
object Dummy {
  // -------------------------------------------------------------------------
  // TOOLS
  // Tools are executable functions that perform specific actions or computations. They are designed to be called by clients to execute operations.
  // Use cases: Mathematical calculations, data processing, API calls, file operations, system commands.
  @Tool(name = Some("add"), description = Some("Add two numbers"))
  def add(
    @ToolParam("First operand") a: Double,
    @ToolParam("Second operand") b: Double
  ): Double = a + b

  @Tool(name = Some("multiply"), description = Some("Multiply two numbers"))
  def multiply(
    @ToolParam("First operand") a: Double,
    @ToolParam("Second operand") b: Double
  ): Double = a * b

  @Tool(name = Some("hello"), description = Some("Say hello"))
  def hello(): String = "Hello, world!"

  @Tool(name = Some("loremipsum"), description = Some("Generate a lorem-ipsum message"))
  def generateLoremIpsum(): String = {
    loremipsum.LoremIpsum.generate(42 * 6).map(_.text()).mkString("\n\n")
  }

  // -------------------------------------------------------------------------
  // PROMPTS
  // Prompts are template generators that create structured text or instructions, typically for use with language models.
  // Use cases: Message templates, instruction generation, context formatting, prompt engineering.

  @Prompt(name = Some("greet"), description = Some("Generate a greeting message"))
  def greet(@PromptParam("Name to greet") name: String): String = {
    s"Hello, $name!"
  }

  @Prompt(name = Some("farewell"), description = Some("Generate a farewell message"))
  def farewell(@PromptParam("Name to say goodbye to") name: String): String = {
    s"Goodbye, $name! Thank you for using our MCP server."
  }

  // -------------------------------------------------------------------------
  // RESOURCES
  // Resources represent data sources or content that can be accessed by clients. They provide read-only access to information.
  // Examples: Files, databases, APIs, configuration data, documentation, logs.

}

object ExampleServer extends ZIOAppDefault {
  override def run = {
    val settings = FastMcpServerSettings(
      debug = true,
      logLevel = "DEBUG"
    )
    for {
      server <- ZIO.succeed(FastMcpServer(name = "dummy-mcp-server", settings = settings))
      _      <- ZIO.attempt(server.scanAnnotations[Dummy.type])
      // _       <- ZIO.log("Starting stdio server...")
      _      <- server
                  .runStdio()
                  .tapError(error => ZIO.log(s"Error running stdio: $error"))
                  .onInterrupt(ZIO.log("Server interrupted"))

    } yield ()
  }
}

ExampleServer.main(args)