Environmental services provided by permanent grasslands are well acknowledged but the agricultural services they provide remain difficult to assess with conventional methods. Our objective is to present the step-by-step approach which was used to build a toolbox. Methodologies and concepts developed in functional ecology were mobilized together with long-term partnership with farmers, advisors and teachers. The five tools rely on a common base, the functional characterization of vegetation. These tools make it possible to characterize the agronomic potential of the grassland, to define the range of practices compatible with a vegetation type, to model different scenarios for learning purposes and to estimate room for manoeuvring for a better valorisation of available forage resources. We demonstrate how the different partnerships and the real life situation of knowledge with partners orientated the choices we made and allowed us to pass from a concept with several prototypes to a combination of actionable, ie easily mobilized, tools. We analyze the different types of training available for scientists and practitioners in this work. Finally, we discuss methodological teachings for tool co-construction in action when scientific and practical knowledge on processes are missing.