Agile methodologies are based on effective communication with the customer. The ideal case is XPs on-site customer. Unfortunately, in practice customer representatives are too busy to work with the development team all the time. Moreover, frequently there are many of them and each representative has only partial domain knowledge. To cope with this we introduced to our projects a proxy-customer role resembling RUPs Analyst and we equipped him with a tool, called UC Workbench, that supports the communication with the customer representatives and the developers. Analyst collects user stories from customer representatives and translates them into use cases. UC Workbench contains among other things a use-case editor and a generator of mockups (a mockup generated by UC Workbench animates use-cases and illustrates them with screen designs).