Claude Code's system prompt: what governs its behavior (rastrigin.systems)

A recent analysis has revealed the intricate workings of Claude Code's system prompt, shedding light on its behavioral governance. The prompt consists of two blocks: the first establishes Claude's identity as a "Claude agent" built on Anthropic's Claude Agent SDK, while the second delivers a comprehensive instruction manual exceeding 15,000 tokens. This manual outlines critical security policies and operational standards, emphasizing the context of use—softening restrictions in approved environments like penetration testing and educational CTF challenges. Importantly, the manual reinforces that security practices must always occur within an authorized framework, addressing a potential ambiguity that could lead to over-cautious responses from the model. The significance of this design lies in its layered approach to user interaction and task management. By combining static instructions with dynamic reminders, Claude Code is better equipped to engage users effectively and contextually. For example, it proactively encourages the use of its TodoWrite tool for task tracking, even outside explicit commands. This innovative design not only enhances the model's utility and responsiveness but also clarifies operational boundaries, ensuring users can safely leverage its capabilities in sensitive areas of security research and code development. This detailed architecture could serve as a benchmark for future AI/ML applications seeking to balance flexibility with ethical constraints.