zio-ella
About
zio-ella is a framework for writing MCP (Model Context Protocol) servers for modern AI platforms using Scala 3 and ZIO with zio-http. It is designed for developers who want to expose ZIO-based services as MCP tools.
Details
- Author
- otobrglez
- GitHub stars
- 3
- Downloads
- 187
- Categories
- Other
Jump to
- Write MCP servers in Scala 3 with ZIO and zio-http
- Define tools using Tool and ArgDef with ZIO effects
- Run via MCPServer and standard ZIOAppDefault pattern
- Port configuration through ZIO config layers
- Lightweight, early-phase framework open to rapid change
Define server capabilities by mapping Tool instances to ZIO effects, then run the server with MCPServer(capabilities).run. The server port can be configured via a ZIO config layer using Config.int("port"). The entry point is a standard ZIOAppDefault that provides the configured server layer.
zio-ella
[zio-ella] is a framework for writing [MCP (Model Context Protocol)][mcp] servers for modern AI platforms with Scala 3
and [ZIO] with zio-http.
> ⚠️ The project is in its early phase and is bound to rapid change. Please feel free to reach-out with ideas and use-cases.
Example capabilities and tools definition within a service might look like:
``scala 3
import zio.ZIO
import zio.dev.ella.*
object MyService:
val capabilities = Capabilities(
// Tool that only returns current server time
Tool("get-time") -> { _ =>
zio.Clock.instant.map(_.toString)
},
// Exemple tool to get where we accept city as an argument.
Tool("get-weather", ArgDef.string("city")) -> {
_.string("city").flatMap(city => ZIO.succeed(s"Weather in $city is sunny!"))
}
)
def run = MCPServer(capabilities).run
Integration with the ZIO Stack as follows:
object Main extends ZIOAppDefault:
def program = for
_ <- logInfo("Booting...")
_ <- MyService.run
yield ()
def configuredServer: TaskLayer[Server] =
ZLayer
.fromZIO(ZIO.config(Config.int("port")).tap(port => logInfo(s"Starting server on port $port")))
.flatMap(portEnv => Server.defaultWithPort(portEnv.get))
def run = program.provide(configuredServer)
``
Resources
- MCP Protocol Tutorial
- Anthropic / Model Context Protocol (MCP)
- MCP Inspector
[ZIO]: https://zio.dev
[zio-ella]: https://github.com/otobrglez/zio-ella
[mcp]: https://modelcontextprotocol.io/introduction
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