The agent the caller is to talk to (the persona; the host resolves the voice front-end that speaks as it).
OptionalBriefWhen taking over: what the agent that is leaving says about the conversation. Absent when starting a conversation.
OptionalPreviousWhen taking over: the agent that is handing over.
OptionalRealtimeOptional per-session realtime model override (a developer's choice in the Meet UI).
OptionalRealtimeOptional per-session voice override.
Asks the host to put an AI agent into the room, either to take a conversation over or to start one.