Function add_tools 

pub(crate) fn add_tools(
    builder: McpServerBuilder,
    facade: Arc<dyn TasksFacade>,
    slot: SessionSlot,
    lead: bool,
) -> McpServerBuilder

Attach the task tools to an existing McpServerBuilder. Called for BOTH lead and worker sessions (tasks are any-caller), so build_forge_server invokes this unconditionally.