The agile manifesto should remind us that we don’t always have to do it the “traditional” way. As product managers, we should be doing whatever is required to tell the story of the customer. Try different things: experiment, explore, then do what works best for you and your team in the context that you might be working in. What do I mean by this?
If it means you can have several discussions and sketch something on a bit of paper – then do it.
What if you could get everyone (including the customer) in a room and do a user story mapping exercise? If that communicates the problems well, then you probably don’t need to go much further.
Or what if you can vist the customer in their context as they use your product? Could you get your engineers and designers to sit next to the customer to listen and observe their problems?
Another option would be to grab the product triad (a Product Manager, Engineer and a Designer) for a quick stand-up, sketch, discuss and make some quick decisions on the spot.
Need to explore some more? Try running a workshop where you gather key stakeholders and do lots and lots of whiteboarding or even paper prototyping to dive deep into understanding the problems you are trying to solve and how you could solve those problems.