Grants: a principal that serves tools subscribes $SRV.PING/$SRV.INFO and those questions under
each name it serves — its own and no other's; the tool runtime and people may ask. The controller
answers discovery for the mesh-controller seat in NATS's services format, one endpoint per verb it
serves, with the seat's description and schema. module list --json says which modules declare tools,
so the console expects an announcement only from those.
The console's discovery reads the machines and the modules; parsing a printed column breaks when it
is reworded. Both now answer JSON on --json, as status and seats do, and the seat verbs ask for it.