[intrepidhero]

A phone (or a video) call has no more overhead and is no more of a bother than walking over to someone's cube for a chat. I understand that it feels like more to a lot of people but I don't think it is, objectively, more of a bother for either party. If you need the back and forth interactivity to clarify your question then do it.

Your trick with a shared doc is also a great idea and has two additional benefits. 1. The act of writing is an extra step to help you clarify your question. 2. The question and answer are now documented for the future. Both big wins versus a quick chat that then needs to be written down.