We are working towards a universal language to communicate about the dynamics of global systems and the complex decision making necessary to produce good policy advice. Such formal domain-specific language will be employed by Rapid Assessment Tools that support a visual and participatory way of model building. The tools are to be used in difficult situations that involve the participation of different stakeholders in decision making and policy design. Under the hood, Constraint Technology will support active, goal-directed problem solving. As a test case, the problem of Climate Resilient Urban Design is being studied.