Selecting a library from a vast ecosystem can be a daunting task. The libraries are not only numerous, but they also lack an enumeration of the features they offer. A feature enumeration for each library in an ecosystem would help developers select the most appropriate library for the task at hand. Within this enumeration, a library feature could take the form of a brief description together with the API references through which the feature can be reused. This paper presents LiFUSO, a tool that leverages Stack Overflow posts to compute a list of such features for a given library. Each feature corresponds to a cluster of related API references based on the similarity of the Stack Overflow posts in which they occur. Once LiFUSO has extracted such a cluster of posts, it applies natural language processing to describe the corresponding feature. We describe the engineering aspects of the tool, and illustrate its usage through a preliminary case study in which we compare the features uncovered for two competing libraries within the same domain. An executable version of the tool is available at https://github.com/softwarelanguageslab/lifuso and its demon- stration video is accessible at https://youtu.be/tDE1LWa86cA.