LEVEL 03 · LESSON 21
System prompts
System prompts guide behavior; application controls enforce authority.
What it is
A system prompt is an instruction supplied by the application to define the model’s role, priorities, and expected behavior. Products differ in how they name and prioritize instruction layers.
Why it matters
Shared instructions make behavior more consistent across users, but they do not replace enforcement in the application.
A business example
A support assistant is instructed to use approved policy sources, distinguish facts from assumptions, and ask for missing order details. Those directions guide its replies across many conversations.
How it actually works
The application includes persistent instructions alongside each request. Clear instructions define the task, relevant constraints, evidence expectations, and what to do when information is missing. Separate instructions from untrusted documents and test conflicting requests. Version prompts so changes can be evaluated and rolled back. Keep actual secrets and permission enforcement outside the prompt: text instructions are not a secure vault or an access-control system.
A common misconception
A system prompt saying ‘never disclose sensitive data’ cannot guarantee that sensitive data is safe to place in the model’s context.
ONE SENTENCE TO REMEMBER
System prompts guide behavior; application controls enforce authority.
CHECK YOUR UNDERSTANDING
A team wants its internal assistant to protect salary data. Which approach is sound?
Show the answer
Answer: C.
System prompts guide behavior; application controls enforce authority. A prompt is not a secure vault or an access-control system, so it cannot guarantee that sensitive data is safe to place in the model’s context.
Take it into your next meeting
Which instruction in your assistant is actually a business rule that needs code-level enforcement?
One more concept, understood.
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