Ensuring that users can successfully perform their primary tasks and achieve their behavioral goals is critical for the success of persuasive system. Are user manuals needed to achieve this goal? In this paper, we sought to understand the role of end-user documentation for persuasive systems. 50 persuasive apps from the Google Play Store were analysed to determine the importance of user manuals or guides for persuasive health apps. Although based on a small data set, our results show that in most cases persuasive systems need user documentation and hence we encourage developers of such systems to allocate resources for creating quality documentation for their users.