The Contagious skill brings the science of virality to Claude, based on Jonah Berger's STEPPS framework (Social Currency, Triggers, Emotion, Public, Practical Value, and Stories). It allows developers and marketers to systematically engineer word-of-mouth into their products, features, and content. By analyzing offerings through the lens of human psychology and environmental triggers, the skill provides a 0-10 shareability score and offers specific, actionable improvements. It is ideal for anyone looking to move beyond 'luck' and use proven behavioral science to increase user acquisition and organic sharing.