Define an MCP server.

defmodule MyApp.MCP do
  use Noizu.MCP.Server,
    name: "myapp",
    version: "1.0.0",
    instructions: "Weather and reporting tools for MyApp."

  tool MyApp.MCP.GetWeather
  tool MyApp.MCP.SendEmail, name: "send_email_v2"
  resource MyApp.MCP.Config
  resource_template MyApp.MCP.TableSchema
  prompt MyApp.MCP.CodeReview
end

use Noizu.MCP.Server makes the module a supervisable child (children = [{MyApp.MCP, transport: :stdio}]), registers components declared with tool/2, resource/2, resource_template/2, and prompt/2, derives the server's capabilities automatically, and provides notification helpers:

MyApp.MCP.notify_changed(:tools)                    # list-changed fan-out
MyApp.MCP.notify_resource_updated("config://app")   # to subscribed sessions

use options

• :name (required) — server name advertised in serverInfo
• :version (required) — server version string
• :title, :description, :website_url, :icons — optional serverInfo metadata
• :instructions — usage hints delivered to the client on initialize

Escape hatch: behaviours without macros

Everything the DSL generates is an implementation of this module's behaviour. Skip the component registrations and implement the handle_* callbacks directly; implementing a callback is what enables the corresponding capability:

defmodule MyApp.RawMCP do
  use Noizu.MCP.Server, name: "raw", version: "1.0.0"

  @impl true
  def handle_list_tools(_cursor, _ctx),
    do: {:ok, [%Noizu.MCP.Types.Tool{name: "echo"}], nil}

  @impl true
  def handle_call_tool("echo", args, _ctx),
    do: {:ok, inspect(args)}
end

Behaviour-level handlers receive string-keyed, unvalidated arguments — validation/casting is part of the component DSL layer.