This paper describes how the Prometheus Design Tool (PDT) is used to support the Prometheus methodology for designing agent systems. This is done by using an exemplar system that has been used previously in the literature, and is briefly described earlier in this volume. This paper presents the development of a design for this system using PDT. By using different tools and methodologies to design the same example system it is easier to observe the similarities and differences between both the methodologies and the tools supporting them. Prometheus and PDT, like the other systems presented in this volume, has specific strengths and features that have been developed to support the design process. However it is also evident that there is a great deal of commonality across agent methodologies that should give developers confidence that there is in fact an emerging agreed understanding as to the important aspects of designing and developing agent systems.