Problem analysis has long been considered the key to requirements engineering, and the Problem Frames (PF) approach provides a structured method by deploying a common model for analyzing various types of problems. Problem decomposition is an important technique in structuring the software solution and also the key to reducing problem size and complexity. However, there has not been a suite of flexible and effective tools to describe details of problem domains in PF models. In this paper, we combine model-driven engineering and PF to provide a tool that can refine domain descriptions. In order to support collaborative modeling between domain stakeholders and software designers, we provide a technique and tool to allow the modeller to zoom in the details of a problem diagram, by adding UML State Machine Diagrams and SysML Block Definition Diagrams to domain descriptions. A demo video of this tool is available at https://youtu.be/BcQPlDYiOa8