Towards Safer Chatbots: Automated Policy Compliance Evaluation of Custom GPTs
David Rodriguez, William Seymour, Jose M. Del Alamo, Jose Such
TL;DR
The paper tackles the challenge of enforcing policy compliance for user-configured GPTs in a rapidly growing GPT Store. It introduces a fully automated, black-box framework that discovers Custom GPTs, generates policy-aligned red-teaming prompts, and uses an LLM as a judge to assess compliance, validated against human annotations (F1 ≈ 0.975) and applied to 782 GPTs. The large-scale study reveals that 58.7% of evaluated GPTs violate at least one policy, with domain variation: romantic GPTs are highly non-compliant while cybersecurity-focused GPTs are largely compliant; most violations resemble base-model behaviors and are amplified by customization. The work demonstrates the feasibility and cost-effectiveness of behavior-based policy evaluation at scale, exposes governance gaps in current GPT Store reviews, and discusses implications for platform safety, responsible disclosure, and broader applicability to other LLM ecosystems.
Abstract
User-configured chatbots built on top of large language models are increasingly available through centralized marketplaces such as OpenAI's GPT Store. While these platforms enforce usage policies intended to prevent harmful or inappropriate behavior, the scale and opacity of customized chatbots make systematic policy enforcement challenging. As a result, policy-violating chatbots continue to remain publicly accessible despite existing review processes. This paper presents a fully automated method for evaluating the compliance of Custom GPTs with its marketplace usage policy using black-box interaction. The method combines large-scale GPT discovery, policy-driven red-teaming prompts, and automated compliance assessment using an LLM-as-a-judge. We focus on three policy-relevant domains explicitly addressed in OpenAI's usage policies: Romantic, Cybersecurity, and Academic GPTs. We validate our compliance assessment component against a human-annotated ground-truth dataset, achieving an F1 score of 0.975 for binary policy violation detection. We then apply the method in a large-scale empirical study of 782 Custom GPTs retrieved from the GPT Store. The results show that 58.7% of the evaluated GPTs exhibit at least one policy-violating response, with substantial variation across policy domains. A comparison with the base models (GPT-4 and GPT-4o) indicates that most violations originate from model-level behavior, while customization tends to amplify these tendencies rather than create new failure modes. Our findings reveal limitations in current review mechanisms for user-configured chatbots and demonstrate the feasibility of scalable, behavior-based policy compliance evaluation.
