In this paper we investigate how agents can facilitate and mediate interaction, communication and cooperation among participants of spatially distributed teams. We illustrate the architecture of an agent mediated-collaborative system that can serve the role of a tutor within a virtual group. In the virtual group the software agent should play besides the tutoring role also the group management role. The group manager has the responsibility to control the coherence of the actual group in regard to the actual group structure definition. This research will highlight also the incorporation of social-filter algorithms to mental models of software animated agents. Those algorithms may qualify an agent's expression of its emotional state by the social context, thereby enhancing the agent's believability not only as a tutor but also as a conversational partner or virtual teammate.