True when no preference is set (so CreateMessageRequest.toJson can omit the whole modelPreferences object).
0..1: importance of minimizing cost
ordered model name hints, most preferred first
0..1: importance of capability
0..1: importance of minimizing latency
The server's preferences for model selection during sampling. All fields are optional. The priority values, when set, are clamped at the wire boundary to the spec's 0..1 range by the consuming client.