There is a need for a platform to evaluate planned air-rail multimodal networks. The Strategic Multimodal Evaluator, developed within the MultiModX project, enables the assessment of mobility network performance by considering various factors, such as flight schedules, rail timetables, infrastructure (access, egress, and minimum connecting times), policies, and passenger preferences. Using a graph-based approach, it computes mono- and multimodal itineraries, clusters equivalent alternatives from a passenger perspective, distributes demand across these clusters, and assigns passengers to itineraries respecting vehicle capacities. Finally, it computes key performance indicators such as travel time, connectivity, and network efficiency. The Evaluator serves as a what-if analysis tool for strategic multimodal network assessment. A case study on intra-Spain mobility will demonstrate its capability to analyze policies like short-haul flight bans and their effects on regional accessibility.