Global resource scarcity drives the need for sustainable, circular product development, yet this remains challenging due to complex interdependencies in modern designs. Model-based software can address these challenges by mapping dependencies and evaluating circular economy performance and sustainability. To ensure effective tool development, user roles must be clearly defined to protect sensitive data, enhance user experience, and align workflows with stakeholder needs. This paper, part of the Cyclometric project, introduces a methodology for defining user roles in model-based tools and presents a formal evaluation of the developed roles.