The deployment of multi-agent systems demands for justified confidence into their behaviour, both with respect to correct results of computations and with respect to timeliness thereof. Depending on the the development process different mechanisms and abstractions are needed to facilitate the rigorous evaluation of interacting agents. We propose a modelling and simulation framework for supporting the development process of multi-agent systems; from specification and implementation. Therefore, experimental set-ups are needed that allow an incremental refinement of agents while providing rigorous observation facilities. The benefit of using modelling and simulation for evaluating cooperative agents is illustrated using a simple example based on the Contract Net Protocol.