This paper addresses the MASQUE multi-agent framework for generating alternative plans in local land-use planning, In this framework agents represent land-use experts and initiate the development of plan proposals and request each other to express their claims in order to incrementally draw up these proposals. Presented is a probabilistic approach to the implementation of those agents to enable them to make decisions under uncertainty. It is described what personal and collective beliefs they construct and use in order to strategically choose their actions. Negotiation takes place between the initiating agent and the others in order to reach agreement on the incorporation of the claims. The negotiation is organized as an iterative process in which both parties consider conciliatory adjustments of their strategies, and thus their decisions, in order to try to find mutually accepted solutions.