The brief is where you say who the agent is and what it may do. It composes and publishes into the system prompt, which means two things worth remembering:
- Edit the brief, never the prompt. The next publish overwrites the prompt.
- Nothing you write here is live until you publish.
What a good brief contains
Section titled “What a good brief contains”Identity. One or two sentences. Who does this agent answer for, and in what tone. Resist the temptation to write a personality essay. The model is already good at sounding human, and every extra adjective competes for attention with your actual rules.
Scope. What it may answer, and what it must not. Be concrete. “Do not give medical advice” is a rule. “Be careful with sensitive topics” is a mood.
Handover rules. The single highest-value section, and the most commonly vague. Name the situations:
Hand over to a human for refunds, complaints, anything about an existing order, and any question about a price that is not in the catalog.
“Hand over when unsure” fails because a model is rarely unsure. That is the whole difficulty.
Format. Chat is not email. Ask for short answers, and say so explicitly.
What to leave out
Section titled “What to leave out”Facts. The brief is instructions, not knowledge. Prices, hours and policies belong in knowledge or the catalog, where you can change them without republishing the agent and where the answer can cite a source.
A brief that contains your opening hours will be wrong in six months, confidently and in the agent’s own voice.
Test the brief, not the prose
Section titled “Test the brief, not the prose”A brief reads well and still behaves badly. The only check that counts is running your real questions through Testing and seeing what comes out.
Change one thing at a time. If you rewrite the identity, the scope and the handover rules together and the agent gets worse, you have learned nothing except that it got worse.