Using scientifically grounded foundations is one of the fundamental principles in design science research in order to strengthen research rigor. However, issues around using knowledge which does not undoubtedly belong to these foundations are hardly discussed. The paper addresses one of these issues by suggesting a tool called TAVIAS. The approach supports researchers conducting design science research on the basis of existing artifacts that may not belong to these foundations. The tool proposed is intended to strengthen the researcher's awareness on whether or not and to what extent artifacts he or she intends to use should undergo further evaluation. This is done by identifying the overall portfolio of input artifacts, assessing each of them along a scoring model and visualizing the artifacts' suitability from a research rigor perspective. Thus, the researcher's focus is guided onto the artifacts that need further attention and the overall rigor of artifact selection itself is enhanced.