This research in progress aims at identifying a set of design guide-lines to perform rapid diagnostic of common ground among participants of a startup team and their coach. Previous studies have shown that teams with high common ground are more efficient. Nonetheless, no existing tool can rapidly monitor its progression and visualize it in a simple way to allow the coach to perform team diagnostic. In this paper we present a prototype, which monitors the evolution of joint objectives and joint resources among team members and that represents the updated path of a startup team in less than five minutes. Em-pirical data collected at a startup weekend shows that it is possible (a) to rapidly monitor the evolution of common ground within the team, (b) to intervene whenever the joint commitment of participants gets too low and (c) positively affect the performance of a startup team.