Well, a rough design would itself be a list of features/milestones and maybe an overall direction of how the player should interact with the module. There are games where a player spends hours in an inventory comparing items and games where switching items is a matter of pressing a button. It’s hard to ask for the details of the blueprint when the blueprint does not exist yet so it is a matter of the competence of the designer and the communication between the designer and the director. You yourself need to present some clarification on what you expect the end result to be and the designer should handle the backtesting and finding flaws. It should be user-friendly and follow the “blueprint best practices”. Those are my thoughts on the subject.