This paper addresses the link between data, metrics, and the paths from cause to effect in urban sustainability and livability frameworks. The first section thoroughly discusses the different existing frameworks for evaluating sustainability and livability goals for urban communities. In the results section, a qualitative and quantitative analysis of a comprehensive list of frameworks that evaluate sustainability and livability in cities is elaborated, with a thorough post-process of the different schemes from an epistemological perspective to analyze the subjectivities implicit in any urban-level sustainability framework. Finally, in the discussion section, two main aspects are tackled. The first is the development of a proposal for a set of indicators that incorporates the best of the different frameworks analyzed. The second aspect deals with the methodology of implementation of these frameworks. Here, the authors point out the weaknesses of current urban-level sustainability frameworks and their main components, and they propose a set of criteria to overcome the different detected gaps. All these steps have helped the authors establish a clear roadmap for developing the platform TOOLS4Cities that can help set a future reference methodology for urban sustainability evaluation.