OptionalBehaviorPreferred function-calling behavior.
OptionalSupportsWhether synchronous blocking tool execution is legal. Absent = permitted. false on models that
reject blocking mode outright (Gemini 3.8 Live Extended Thinking).
OptionalSupportsWhether per-function scheduling hints are legal (Gemini SILENT / WHEN_IDLE / INTERRUPTED).
Absent = not supported.
Tool-execution semantics a model permits. Capability declarations, not requests.