Adults adjust the informativeness of their utterances to the needs of their addressee. For children, however, relevant evidence is mixed. In this article we explore the communicative circumstances under which children offer informative descriptions. In Experiment 1, 4- and 5-year-old children and adults described a target event from a pair of almost identical events to a passive confederate listener who could either see or not see the referents. Adults provided disambiguating information that picked out the target event but children massively failed to do so (even though 5-year-olds were more informative than 4-year-olds). Furthermore, both children and adults were more likely to mention atypical than typical disambiguating event components. Because of the contrastive nature of the task, the listener's visual access had no effects on production. Experiment 2 was a more interactive version of Experiment 1 where participants played a guessing game with a "naïve" listener. In this context, children (and adults) became overall more informative, and the difference between child groups disappeared. We conclude that the informativeness of children's event descriptions is heavily context-dependent and is boosted when children engage in a collaborative interaction with a "true" interlocutor.