I don't know why you'd choose to use it if you had no idea what it's doing differently. It could just be a round robin/random picker, or based on which of their APIs aren't getting used much.
And then you're sending massive refactoring tasks to a model that can't handle them and waste money on Claude 4.5 when the user asks the model to edit the readme
There has to be some kind of evaluation, it _can_ be just good old if statements. But it's definitely not a "what's cheapest" round robin =)
And I'm guessing it's a) proprietary b) changing so fast that there's no point in documenting it.