I am reviewing it. They are not structural plans. I am reviewing against IBC/IRC. It is required and they clearly state it can be done by an architect or engineer.
I think you need to confirm "What does your stamp imply" for the drawings submitted. First, if there is no structural information, you are reviewing for "part" of IRC, not all of IRC. IRC has framing member sizes. Is your stamp implying it meets all of IRC, that includes mechanical, egress, structural, foundations etc.?
They require a stamp because they want a responsible party to supervise and seal the design, not say "I officially okay nothing". I am not a lawyer, but I know many, and they thrive by making you sound REALLY IRRESPONSIBLE to a jury when something happens. My favorite was "a
minor child fell through the rotted porch floor you failed to find". I was envisioning a child with pigtails and braces. When I met the minor child, he was 15 and on a high school football scholarship to a private school and looked like Refrigerator Perry. But he was a "Minor child".
So, here are 2 for you to consider how you would answer:
1) You did not contact the person who designed and drew these drawings to confirm any details or specifics of their design? Do you consider that to be "Due Diligence" and "Due Care". I mean, the drawings do not even say what type of wood to use for structural framing. Of course, they will not ask you that until after they have had you admit how important structural framing is to safety.
2) If you are stamping essentially no structural information, are you not participating in an effort to deceive the local building officials? Again, only after having you admit that the purpose of city inspection, oversight and jurisdiction is to ensure public safety?
I promise you, they will have no less than 20 more similar but on other topics.