Working with requirements means dealing with problems related to incomplete or faulty textual specifications. Specifications are created in various types and combinations such as models, drawings, and textual documents. The information gap between the specification and the implementation of any (software) system leads to delays, mistakes, and high costs due to problems in the production stages. Therefore, the earlier specifications are corrected and improved, the better. We providea tool called RESI to support analysts while working with textual specifications. RESI considers many of the directives to be followed when processing customer specifications. It offers a dialog-system which makes suggestions and inquires the user when parts of the specification are ambiguous, faulty or inaccurate. RESI utilizes various ontologies to discover such problems and to deliver common sense solutions.