OEM pod shell — what do you actually need in a capability brief?

We are a small US brand looking at a custom pod silhouette, not a full box mod. Factory asked for a capability brief and I do not want to send a vague mood board.

From threads on sourcing boards, people mention mouthpiece angle, fill port placement, coil compatibility, and whether the pod is proprietary or works with an existing platform.

We care about child-resistant fill, clear labeling space, and a finish that does not chip in a pocket. Nicotine is handled separately on our side — this is hardware only.

If you have shipped a similar brief, what sections did the factory push back on?