The study examines the effectiveness of the MindCraft app, which uses artificial intelligence to monitor adolescent mental health through active and passive data collection. This is a randomized controlled trial with three groups of students aged 14-19 from British secondary schools. Participants are divided into a group receiving personalized AI recommendations, a group receiving general recommendations, and a control group with self-monitoring only. The primary outcome is the Strengths and Difficulties Questionnaire score, with secondary outcomes measuring eating disorders, sleep, self-harm, and well-being. The study lasts four weeks with follow-up at one month. Researchers hypothesize that personalized AI recommendations will have a greater positive effect on mental health outcomes than general recommendations or self-monitoring alone.