Why it matters for your business
The system prompt is effectively the job description for an AI assistant, and many quality problems trace back to it: vague rules, conflicting instructions or missing escalation paths. It deserves the same review as any customer-facing policy, because it shapes every conversation. It is not a security boundary, though. Users can sometimes coax a model into ignoring or revealing its instructions, so anything that must never happen, such as issuing a refund over a limit, should be enforced in code and permissions, not only in the system prompt.
Example
A dental practice's scheduling assistant has a system prompt that sets a friendly, brief tone, lists the services and insurance plans the practice accepts, tells the assistant never to give clinical advice and requires a handoff to staff for billing disputes. The booking itself goes through a tool that only offers real open slots.