This guide shows you how to write clear, reliable behaviour rules for your AI Phone Assistant. This is sometimes called Prompt Engineering, and is the same skill set you would use with a tool like ChatGPT, Claude or Gemini.
The goal is consistency: the assistant should behave like a well-trained team member across common scenarios such as complaints, emergencies, out of scope, and tool use.
1) Start with the outcome, then write “if, then” rules
If your instruction does not specify when it applies and what success looks like, the assistant will improvise.
❌ Bad
Make sure you understand what the customer wants and help them quickly.
✅ Good
If the customer’s request is unclear, ask one clarifying question. Then provide the shortest correct answer you can. If you still cannot determine what they need, offer two options the customer can choose from.
2) Write as if you are speaking directly to the assistant
Avoid describing what the assistant “should do”, tell it exactly what to do.
❌ Bad
The assistant should avoid being too wordy and it should not be pushy.
✅ Good
Use short replies. Ask one question at a time. Do not upsell. Do not suggest extra products or services unless the customer asks.
3) Keep each rule single-purpose, split mixed instructions
When you bundle multiple goals into one paragraph, the assistant will miss steps or prioritise the wrong thing.
❌ Bad
Be friendly, answer questions, use tools where possible, and handle complaints appropriately.
✅ Good
Tone: Use a warm, professional tone. Keep replies concise.
Tool use: Use tools only when needed to answer the customer’s request. Complaints: Acknowledge frustration, gather key details, then explain next steps.
4) Tool use rules: define triggers, inputs, and what to do on failure
For your AI Phone Assistant, integrating to your systems (called "tool use") can be extremely effective, but only when you constrain them.
4.1 Look up order
❌ Bad
Use the order lookup tool whenever an order is mentioned.
✅ Good
Only use the order lookup tool when the customer asks for an update, status, delivery timing, tracking, or order details. Before using the tool, ask for the minimum identifier you need (for example: order number, email address). After using the tool, summarise the result in one short paragraph and offer the next best step. If the tool returns no result, ask for one alternative identifier, then stop and explain you cannot locate it yet.
4.2 Send SMS
❌ Bad
Offer to send a text summary to everyone to be helpful.
✅ Good
Only send an SMS if the customer explicitly asks for a text, or explicitly agrees after you offer it in the moment. Do not ask for SMS consent unless texting has come up naturally. Before sending, confirm the mobile number and what you are about to send in one sentence. Do not include sensitive personal details in SMS.
5) Complaints and frustration: acknowledge, then move to resolution
The best prompts prevent arguments and keep the assistant calm and useful.
❌ Bad
Stay professional. Do not apologise too much.
✅ Good
If the customer is frustrated or complaining:
1) acknowledge the frustration in one sentence
2) ask one question to identify the issue category (billing, delivery, service quality, other)
3) gather the minimum facts needed to investigate (order reference, date, what happened)
4) explain the next step in plain language
Never argue with the customer or suggest they are wrong. Never blame the customer for the issue.
6) Emergencies: keep it simple, do not improvise
❌ Bad
If it is an emergency, try to help as much as possible and provide guidance.
✅ Good
If the customer describes immediate danger or a medical emergency, instruct them to contact emergency services right now. Do not provide medical, legal, or safety advice beyond that instruction. Then stop the conversation unless the customer confirms they are safe to continue.
7) Out of scope and uncertainty: “do not guess”, offer a safe next step
This is where assistants often sound confident but wrong.
❌ Bad
If you do not know, give your best estimate.
✅ Good
If you are not confident the business has provided the answer, do not guess. Say you do not have that detail. Then offer the next best step: ask a clarifying question, suggest where the customer can find the correct info, or offer to take details for follow-up. Avoid inventing prices, policies, availability, delivery dates, or commitments.
8) Add “negative examples” only when you see misbehaviour
Negative examples are powerful, but too many can confuse the model.
❌ Bad
Do not do this. Do not do that. Do not do something else.
✅ Good
Use negative examples only to stop a specific mistake you have observed. Example: - Do not send an SMS unless the customer asked for a text or agreed after you offered it.