The Jazz won't go into detail, but they'll convince the agent there's a legit chance they will be picking in Mitchell's range. Otherwise, the agent won't send him.
So all you have to do to an agent to get a workout is be like "Oh yeah, we can definitely trade up for him, just trust us"?
No. That doesnt matter. The main thing that matters is Mitchell and his agent/camp believe the Jazz are a good fit and they are happy with that outcome if it happens. Any GM could spin a web of BS that they can trade up if that's all they had to do to get a workout.