Returns a specification to start this module under a supervisor.

See Supervisor.

@spec ensure_tool_registered(String.t() | nil) :: :ok

Ensures the callback tool is registered for the session.

@spec handle_tool(map()) :: map()

Handles callback tool invocations from Python.

@spec invoke(String.t(), list()) :: {:ok, term()} | {:error, term()}

Invokes a registered callback with arguments.

@spec register(function(), pid()) :: {:ok, String.t()}

Registers an Elixir function as a callback.

@spec unregister(String.t()) :: :ok

Unregisters a callback.