Abstract
In this article we show that the communications between agents can be described in terms of dynamic environments of evaluation. We first make this idea clear through an electronic commerce scenario, and then we propose a communication protocol named CRAT that describes the communications between two agents in terms of evaluation environments and scripts. That allows us to introduce dynamic environments in the domain of agents. After that, we show that the use of dynamic environments helps solving some problems occurring when agents have to access data. Finally we observe that the use of dynamic environment make stronger the need to annotate semantically the information exchanged between agents so that the agents can handle unexpected situations.