Although object specification technology is successfully used for modeling information systems, it is not able to get a grasp of dynamically changing behavior. Due to the fact that objects in information systems can have a very long life-span, it often happens that during the life of an object external requirements are changing (e.g. changes of laws or banking rules). Such changes often require the object to adopt another behavior. The main problem for current object specification approaches is that, in general, not all possible changes can be taken into account in advance at specification time. Therefore, a flexible extension is needed to capture this situation. The approach we present and discuss in this paper is an important step towards a specification framework based on the concept of agent by introducing a certain form of knowledge as part of the internal state.