Many K-12 CS education instructors are new to teaching computing and use block-based programming (BBP), allowing them and their students to learn computing concepts with less frustration. Based on prior work with instructors, we found that they need assistance with grading student projects as they are new to coding and developing corresponding assessments. Existing methods are either not intuitive and too restrictive for custom assignments, or tediously unnecessary. Additionally, providing a grading support tool will help increase adoption of our Advanced Placement Computer Science Principles curriculum. Therefore, we began developing a tool to assist teachers with grading BBP projects. This paper reports on a modified User Experience Research method, which we used to determine the critical and necessary features needed for the tool to allow teachers to successfully and efficiently assess BBP student artifacts.