Textual description of requirements is a specification technique that is widely used in industry, where time is key for success. How requirements are specified textually greatly depends on human factors. In order to study how requirements processing is affected by the level of detail in textual descriptions, this paper compares enriched textual requirements specifications with non-enriched ones. To do this, we have conducted an experiment in industry with 19 engineers of CAF (Construcciones y Auxiliares de Ferrocarril), which is a supplier of railway solutions. The experiment is a crossover design that analyzes efficiency, effectiveness, and perceived difficulty starting from a written specification of requirements that subjects must process in order to build software models. The results show that effectiveness and efficiency for enriched requirements are better, while non-enriched requirements are slightly more difficult to deal with. Therefore, even though enriched requirements require more time to be specified, the results are more successfully when using them.