Writing agent instructions

Agent Builder will write instructions for you, and they are a reasonable start. The agents that people keep using are the ones where someone has then tightened the instructions by hand.

Agent Builder allows up to 8,000 characters of instructions. You rarely need that many. You need the right ones.

1. A structure that works

1. Purpose: one sentence on the job.
2. Audience: who uses it and what they already know.
3. Sources: which knowledge to use first and what to do when it is silent.
4. Steps: how to handle a typical request.
5. Format: length, structure, tone, language.
6. Boundaries: what it must never do.
7. Escalation: where to send people when it cannot help.

2. Worked example

Purpose: You help staff at [firm] find answers in our expenses and travel policy.
Audience: All employees. Assume no finance knowledge.
Sources: Use the Finance Policies SharePoint folder first. If the policy does not answer the question, say "The policy doesn't cover this" and do not guess.
Steps: 1) Identify the policy section that applies. 2) Answer in two to four sentences. 3) Quote the section number and title. 4) If there is a limit or approval requirement, state it clearly.
Format: British English, plain language, no more than 120 words unless the user asks for more.
Boundaries: Do not give tax or legal advice. Do not discuss individual employees' claims. Do not invent limits or amounts.
Escalation: For anything not covered, suggest emailing [finance mailbox placeholder].

3. Write instructions you can test

Vague: "Be helpful and accurate." Testable: "Quote the section number in every answer."

If you cannot check whether the agent followed an instruction, rewrite it until you can.

4. Keep a test set

Keep a short list of test questions with the answer you expect. Re-run them every time you change the instructions or the knowledge. This is your quality control, and it makes the jump to Microsoft Copilot Studio, which has built-in evaluations, much easier later.