Optionaltiera POINTER to the served instructions + the pinned hash — never inlined creds, never the full text by default.
The DEFAULT tool surface — RESIDENT routes only, plus a synthetic discover_tools when cold-tail routes exist.
This is the tier-trim: the cheap/lower tier carries a SMALLER tool surface (the conditional context reduction).
COLD-TAIL routes — NOT in the default surface; revealed on demand via discover_tools.
sub-agents → one front-door tool each (dispatched as a NEW completion at the child's tier).
model preference list (cheap→capable) from the primary skill; the OpenRouter ids to try in order.