Future scenarios are intermediary artefacts for mid- and long-term design of complex solutions, e.g., to improve urban mobility systems. They allow designers to explore possible alternatives and incorporate uncertainty in the process. While their making is widely studied and implemented in scenario planning, their assessment got little attention. To find out which characteristics of scenarios we can assess, we conducted interviews and an expert workshop. This results in a scenario assessment framework of 3 levels: Assessment of system impact, evaluation of impact on practitioners and quality assurance. We focus on the latter as it represents the key gap and established a checklist for it. We distinguish between the level of engagement, i.e., scenario makers and users who adapt existing sets (or archetypes). Finally, we provide a checklist to aid ensuring that when choosing existing scenario sets, key criteria are fulfilled. This shall enable designers to better integrate scenarios in their workflows. We provide examples of designing mobility solutions. Yet, the findings can be applied to all disciplines where scenarios can aid design processes but are so far limited due to the resources needed for creating meaningful scenarios.