Model is constrained to always predicting a function call only.
If allowed_function_names is set, the predicted function call will be
limited to any one of allowed_function_names, else the predicted
function call will be any one of the provided function_declarations.
Default model behavior; model decides to predict either a function call or a natural language response.
Model will not predict any function call. Model behavior is same as when not passing any function declarations.
Function calling mode for the model.