Prototyping is a core activity in User-Centered Design (UCD) process and is aimed at supporting iterations of design ideas until all users' requirements are met. Although many dedicated prototyping tools exist, we have found out that most of them lack features for the traceability of information that can be useful for driving the evolution of prototypes. In this paper, we presents a prototyping tool called PANDA which has been specifically conceived to investigate features for dealing with the evolution of prototypes. Herein we present a view at glace about the tool a more specifically annotations mechanisms that can be used for recording design choices, new requirements, fixing design typos, and so on.