Much like wind energy in its early years, marine energy has vast potential, and wave energy converter (WEC) concepts are constantly in development. Consequently, wave energy faces many challenges for expansion and has a wide-ranging design space of WEC concepts. The large design space demands new methods for understanding the potential performance of early-design stage concepts. The Technology Performance Level (TPL) metric has been a proposed method for early-stage concept assessment. However, previous research has shown that the TPL is not designed in such a way that it is able to distinguish between multiple early-stage, low-fidelity concepts. We created a conceptual design tool to complement the TPL assessment to help wave energy developers during the design stage, rather than a quantitative assessment metric. The tool guides marine energy developers during the conceptual design of a wave energy converter by presenting designers with established practices, asking if their concept can meet these practices and constraints, and providing design feedback based on the answers. In this paper, we document the architecture, content, and results from our first tests of the tool. While limited in the number of participants, this study serves as a proof of concept of the tool’s ability to impact design decisions during concept generation. These results also provide insight for further improvement of the tool’s structure and content. Creating awareness of oversights early in the design process will help wave energy developers effectively engage stakeholder requirements, increasing the appeal of a wave energy converter concept to marine energy stakeholders.