Writing instructions for a phone agent people like talking to
The instructions are the agent's job description. Nearly every agent that annoys callers has instructions that are too vague, too long, or written for a chatbot on a screen instead of a voice on a phone. The good news is that writing them well is not a technical skill. It is the same skill as briefing a new receptionist on their first morning. Here is a structure that works, and a full example you can copy.
Four parts, in this order
Every set of instructions we have seen work well has the same four parts.
- Who it is: name, place, one line of personality, the language, and the fact that it is an AI.
- What it does: the three to five jobs, most common first, each with its steps.
- What it must not do: the short list of lines it may never cross, and what to say instead.
- How it hands over: when to fetch a person, to whom, and what to do if nobody answers.
Keep the whole thing under a page. A phone agent reads its instructions on every turn of the conversation. A long, rambling brief makes it slower and vaguer, not smarter.
Who it is, and what it does
Give it a name and a place: "You are Sofie, the phone assistant at Harbour Dental in Aarhus." Then one line of tone: calm, brief, warm. Skip "you are a helpful assistant"; every agent is, and the line tells it nothing. Say which language to speak and that it may switch if the caller does. Say that it announces it is an AI in its first sentence. That is a courtesy and, in a growing number of places, a requirement; we cover both in telling callers they talk to an AI.
For the jobs, write them the way you would explain them to a person. Not "handle appointments" but "ask for the full name, the phone number and what the visit is for; check the calendar before you offer a time; only say booked when the tool confirms; repeat the date and time back." Name the tools it should use at each step. Put facts (hours, prices, addresses) in the knowledge base, not in the instructions, so they can change without a rewrite. Prompt variables such as {name} cover the caller-specific bits.
What it must not do, and how it hands over
The must-nots are short and absolute. No medical advice. No prices it has not been given. Never say "booked" before the tool has confirmed. Never guess opening hours. Never argue. For each one, give it the sentence to say instead. An agent told only what not to do goes quiet or, worse, improvises. This section is also where the hybrid engine earns its keep, because its second model checks each reply against exactly these lines; the post on stopping a voice agent from bluffing explains how.
The handover is the part most people forget. Write down when to fetch a person: an emergency, a caller who asks twice, anything about money or complaints. Say to whom, and what to tell them in one sentence. And say what to do when nobody picks up: come back to the caller, offer a callback or a message, never leave them on hold. An agent that always has a way to a person is an agent people forgive.
A full example: a clinic reception
Change the names, the tool names and the emergency line, and keep the shape.
You are Sofie, the phone assistant at Harbour Dental in Aarhus. You are an AI. Say so in your first sentence, then ask how you can help. Speak Danish unless the caller speaks another language; then switch. Be calm, brief and warm. One question at a time. Never rush. WHAT YOU DO 1. Book, move or cancel appointments. Ask for the caller's full name, phone number and what the visit is for (check-up, cleaning, pain, other). Use check_availability before offering a time. Use book_appointment to book. Only say "booked" after the tool confirms. Then repeat the date and time back and ask if they want a text. 2. Answer practical questions from the knowledge base: opening hours, address, parking, prices for standard treatments, what to bring. If the answer is not there, say so and offer to take a message. 3. Take messages for the dentists. Note the name, the number and the message in the caller's own words. Say when to expect a call back: within one working day. WHAT YOU MUST NOT DO - Do not give medical advice or say what a symptom might be. Say "I can't judge that, but I can book you in" or fetch a person. - Do not quote prices that are not in the knowledge base. - Do not promise a particular dentist unless the calendar confirms it. - Do not argue. If the caller is unhappy, apologise once and offer a person. - Do not ask for a personal identity number over the phone. WHEN TO HAND OVER - Pain right now, bleeding that will not stop, or an accident: say "I'll get a person straight away" and transfer at once. If nobody answers, say that for emergencies they should call 112, and give the out-of-hours number from the knowledge base. - The caller asks for a person: offer the transfer immediately. - Anything about invoices, complaints or insurance: take a message for the practice manager. When you transfer, tell the colleague the caller's name and the reason in one sentence. If no one picks up, come back to the caller and offer a callback or a message. BEFORE YOU END Repeat any booking or message back. Ask if there is anything else. Say goodbye by name.
Habits that keep it good
Write short sentences in the instructions; the agent copies your rhythm. Give one example phrasing for anything you care about, such as how it says goodbye. Test after every change, in the browser first, and read the transcript rather than trusting your memory of the call; our test plan has the full routine. When a caller finds a gap, add one line, not a paragraph. And if you would rather talk than type, the AI Butler in the dashboard drafts the instructions from a description, and you edit from there.
Where NordTell fits
In NordTell the instructions are plain words in the agent editor, with variables like {name}, opening hours and a knowledge base beside them. The agent says it is an AI in its greeting, never says "booked" before the calendar confirms, and keeps a way to a person. With the hybrid engine, a second model checks each reply against your must-nots.