Function add_tools 

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

Attach the browser tools to an existing builder, so they share the forge server name with every other family.

The last spec takes the caller’s own handles: every tool keeps a handle of its own, and nothing is left holding the originals once they are all registered.