Investigating the correlation between information disclosure and consumers’ purchasing decisions is crucial for comprehending consumer behavior mechanisms and stimulating their buying behavior. Drawing upon signaling theory and the “stimulus-organism-response” (S-O-R) model, this research leverages questionnaire responses from 338 consumers. It utilizes Structural Equation Modeling (SEM) to investigate the influence and fundamental mechanisms of environmental information disclosure, consumer trust (competence, benevolence, and integrity), and online purchase intention of green agricultural products. The antecedents required for online purchase intention are identified through the Necessary Condition Analysis (NCA). This research shows that the disclosure of environmental information regarding the origins of green agricultural products positively impacts the purchase intention, with competence trust and benevolence trust being identified as playing intermediary roles in this relationship, while integrity trust does not play a significant mediating role. The disclosure of environmental information about a product’s origin is a necessary condition influencing consumers’ purchasing decisions. Merchants are encouraged to proactively disclose more environmental information regarding green agricultural products and advised to focus on maintaining competence trust and benevolence trust to enhance consumers’ purchase intentions, thereby fostering the advancement of green consumption.