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Getting Started with FsMcp

Prerequisites​

  • .NET 10 SDK (10.0.100 or later)
  • An editor with F# support (VS Code + Ionide, Rider, or Visual Studio)

Verify your SDK:

dotnet --version
# 10.0.100 or higher

Install packages​

Create a new console project and add the server package:

dotnet new console -lang F# -n MyMcpServer
cd MyMcpServer
dotnet add package FsMcp.Server

Other packages you may need later:

dotnet add package FsMcp.Client       # typed client wrapper
dotnet add package FsMcp.Testing      # test helpers + FsCheck generators
dotnet add package FsMcp.TaskApi      # FsToolkit.ErrorHandling pipeline
dotnet add package FsMcp.Server.Http  # HTTP/SSE transport (opt-in ASP.NET)
dotnet add package FsMcp.Sampling     # LLM sampling from server tools

Hello world: minimal MCP server​

Replace Program.fs with:

open FsMcp.Core
open FsMcp.Server

type GreetArgs = { name: string }

let server = mcpServer {
    name "HelloServer"
    version "1.0.0"

    tool (TypedTool.define<GreetArgs> "greet" "Say hello" (fun args -> task {
        return Ok [ Content.text $"Hello, {args.name}!" ]
    }) |> unwrapResult)

    useStdio
}

[<EntryPoint>]
let main _ =
    Server.run server |> fun t -> t.GetAwaiter().GetResult()
    0

That is a complete, working MCP server in 15 lines. TypedTool.define<GreetArgs> auto-generates the JSON Schema from the GreetArgs record (the name field becomes a required string property). unwrapResult extracts the Ok value or throws with a descriptive error if the tool name is invalid.

Build and verify:

dotnet build

Test with Claude Desktop​

Add this to your Claude Desktop config (~/Library/Application Support/Claude/claude_desktop_config.json on macOS, %APPDATA%\Claude\claude_desktop_config.json on Windows):

{
  "mcpServers": {
    "hello": {
      "command": "dotnet",
      "args": ["run", "--project", "/absolute/path/to/MyMcpServer"]
    }
  }
}

Restart Claude Desktop. You should see the "greet" tool available. Ask Claude to greet someone and it will call your server.

Where to go next​