Public libraries have embraced the popularity of maker education and makerspaces by integrating maker education in their program offerings, and by developing makerspaces that enable patrons to tinker and create products. But less attention has been paid to supporting librarians and maker educators in assessing the impact of these spaces. To expand assessment scholarship and practices related to public library makerspaces, we offer two contributions. First, we share findings from a qualitative research study in which we analyzed how 17 library staff and maker educators define success and identify evidence of success in their maker programs. The findings from that study, in conjunction with our collective experience as research partners working with public library makerspaces, laid the foundation for a series of analysis tools we developed to help stakeholders identify the assessment needs of such learning environments. The Properties of Success Analysis Tools (PSA Tools) represent our second contribution; these tools invite library staff and maker educators to reflect on and unpack their definitions of success in order to identify what features a relevant assessment tool should have.