Chimp MCP

An SDK for building MCP (Model Context Protocol) servers and clients in Scala 3 using boilerplate-less, type-safe APIs based on Tapir and sttp, supporting the variety of the Scala ecosystem.

Quickstart

Run a basic MCP server with Netty exposing a simple adder tool:

//> using dep com.softwaremill.chimp::chimp-server:0.3.0
//> using dep com.softwaremill.sttp.tapir::tapir-netty-server-sync:1.13.19

import chimp.server.*
import io.circe.Codec
import sttp.tapir.*
import sttp.tapir.server.netty.sync.NettySyncServer

case class AdderInput(a: Int, b: Int) derives Codec, Schema

@main def server(): Unit =
  val adder = tool("adder").description("Adds two numbers").input[AdderInput]
    .handle(i => Right(s"Result: ${i.a + i.b}"))

  NettySyncServer().port(8080).addEndpoint(mcpEndpoint(List(adder), List("mcp"))).startAndWait()

Connect and invoke the tool as an MCP client:

//> using dep com.softwaremill.chimp::chimp-client:0.3.0
//> using dep com.softwaremill.sttp.client4::core:4.0.24

import chimp.client.*
import chimp.client.transport.HttpTransport
import chimp.protocol.*
import sttp.client4.*
import io.circe.Json

@main def client(): Unit =
  val backend = DefaultSyncBackend()
  val transport = HttpTransport(backend, uri"http://localhost:8080/mcp")
  val client = McpClient(transport, Implementation("my-client", "0.1.0"))

  val result = client.callTool("adder", Json.obj("a" -> Json.fromInt(2), "b" -> Json.fromInt(3)))
  val _ = result.content.collect { case ToolContent.Text(_, text) => println(text) }

  client.close()
  backend.close()

Documentation

Full documentation is available at chimp.softwaremill.com.

Contributing

Contributions are welcome! Please open issues or pull requests.

Commercial Support

We offer commercial support for Chimp and related technologies, as well as development services. Contact us to learn more about our offer!

Copyright

Copyright (C) 2025-2026 SoftwareMill https://softwaremill.com.