The aim of this paper is to contribute to the design of management tools for sustainable agricultural systems that are able to accompany farming practices in anticipating the long-term effects of practices on natural resources management. Its originality is to analyze tools on the basis of their cognitive content as well as their management philosophy and their organizational model. We applied this approach to the main tool (Pastoral Value) used to assess the potential of forage resources in France. Our findings show how the tool strongly shapes practices and how it is adapted by technicians to their situation within the context of the French Central Pyrenees, emphasizing the role of experiential knowledge.