Where do generative AI (GenAI) tools like ChatGPT or Claude stand when it comes to the design of Interactive Digital Narratives (IDNs)? Can they be used to create an IDN from scratch? Or complete typical tasks in narrative design? To answer these questions we first develop a benchmarking framework in collaboration with a group of experts before applying it to create and evaluate the output of GenAI tools. We describe the development of the benchmarking framework, discuss results and consider limitations. The results show that while GenAI tools can be a great asset in IDN design, they are not yet able to replace a human narrative designer. The strength of the current generation of GenAI tools lays in delivering output that can be used for ideation and training, and in some occasions also for production in the hands of an experienced designer. Finally, we consider ethical aspects and future developments. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.