Function add_tools 

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

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