Recent advances in mobile computing technologies mean that mobile tools have the potential to support scenario- based techniques in the workplace, with potential benefits to requirements processes. However, mobile requirements engineering (RE) tools are a new idea, and little is known about their advantages and weaknesses. This paper reports empirical research to explore the use of mobile RE tools in practice. It describes a mobile scenario tool that we developed to discover requirements directly in the user?s work context. It also describes the results from 3 evaluation studies that demonstrate that these tools can support workplace requirements discovery and documentation, although mobile RE tools pose new challenges that remain to be overcome.