The aim of this paper is to contribute to the analysis of management tools for sustainable agricultural systems based on natural resources management from the perspective of a more relevant designing process. This management is faced with uncertainty linked to the lack of knowledge about the ecological effects of agricultural practices. New management modes, which involve longer term forecasts and, especially, adaptive management that is adjusting decisions in the course of action, lead us to question the nature of the management tools. We analyszed the Pastoral Value tool used to assess the potential of forage resources in livestock farms in France with management science concepts to better understand the relationships between the nature of the tool and practices. Our findings show how the concepts and paradigms building the chosen tool, strongly shapes practices and how it can be adapted by technicians to their situation within the context of the French Central Pyrenees, emphasizing the role of experiential knowledge.