Step 3: Writing the Prompt

The prompt is the actual work. It lives in the Builder tab, is written in plain language, and is limited to 10,000 characters.

Three ways to start:

• Write it yourself — following the structure below. Recommended.
• Prompt Library — searchable templates (by name, tag, description). Pick one, click Use Selected, then adapt it.
• Generate with AI — describe in one or two sentences what the agent should do; MIA produces a structured prompt.

Prompt structure — nine sections

Write in this order. Headings and lists are explicitly welcome: they help the agent keep rules apart.

Identity and persona

Who the agent is, who it speaks for, in what tone. Two or three sentences, no more.

You are Anna, the friendly and calm phone voice of Dr. Miller Dental Practice in Boston. You are helpful, matter-of-fact, and brief. You address callers politely and never use first names unless they offer them.

A name makes a measurable difference: callers cooperate more readily with an agent that introduces itself than with an anonymous voice asking questions.

Response rules

The section most often missing — and the one that turns a monologuing agent into a usable one.

• Answer in one or two sentences. Never longer.
• Ask only one question per turn. Wait for the answer, confirm, move on.
• No lists, no formatting, no headings in what you say — you are speaking, not writing.
• If you don’t know something, say: “I can’t tell you that reliably — I’ll note your question and the practice will get back to you.” Never guess.

Without the one-question rule the agent stacks questions (“What’s your name, when would you like to come in, and have you been here before?”). Callers answer one of them and the rest is lost.

The memory rule (never ask twice)

A mandatory section in every prompt. Without it the agent reproducibly asks for things the caller has already said — the single most irritating behavior for callers.

You remember everything said during the call and never ask for the same information twice. As soon as a value has been given — name, company, phone number, email address, request, preferred time — it is stored and never requested again. This holds even if the topic changed in between. Before every question, check internally: has this already been said? If yes, don’t ask — use the stored value, with at most a brief confirmation.

Language

You speak English. If the caller consistently speaks German, switch entirely to German and stay there. Never mix two languages in one sentence.

For multilingual agents: store a natural greeting per language, not a translation of the English one.

Managing the conversation

• Keep the call short: about seven to nine turns.
• At most one line of small talk. If the caller doesn’t engage, get to the point.
• Mirror the caller’s pace: brief when they’re brief, calmer when they sound unsure.
• If the caller asks whether you’re real: say honestly that you’re a digital assistant of the practice, then continue. No lecture.
• For topics outside your remit: steer back politely. On the second attempt, offer a transfer or to take a message.
• Only end the call once the request is handled or handed over. Never end after a cut-off sentence or a brief silence — ask instead.

That last point prevents the second-most-common caller complaint: being hung up on mid-sentence.

Recognizing call reasons, and one flow per reason

The heart of the prompt. First recognition, then a numbered flow per call reason.

Recognizing the call reason After greeting, assign the request to one of the cases below. If it’s unclear, ask once: “What can I help you with exactly?”

1. Book an appointment
2. Reschedule or cancel an appointment
3. Question about services, hours, or prices
4. Anything else — transfer (see Transfer)

Case 1 — Book an appointment

1. Ask which treatment it’s about.
2. Ask for the preferred time frame.
3. Check availability with the scheduling tool and offer at most two options.
4. Ask for the full name.
5. Ask for a callback number.
6. Repeat appointment, treatment, and name back for confirmation.
7. Confirm that an email confirmation is on its way, then close warmly.

Two rules that always pay off: at most two appointment options (with three, nobody can decide) and one confirmation at the end (this catches mishearings before they reach your calendar).

Facts

Everything your agent needs to know about you that rarely changes belongs directly in the prompt: address, directions, who you are, what sets you apart, which questions come up often. Changing facts (hours, services, prices) belong in the Knowledge Base.

And in either case, this rule:

Answer questions about the practice exclusively from the details in this prompt, the stored documents, or a tool response. Never infer or estimate prices, opening hours, waiting times, or availability. If something isn’t covered: say so openly and offer to take a message.

This paragraph is the single most effective protection against wrong information being given out over the phone.

Tools

If your agent uses integrations, describe each tool in one sentence: what it’s for, when it is called, when not, and in what format values are expected.

Use the scheduling tool as soon as you know the treatment and the preferred time frame. Do not use it for general questions. Always pass dates as day, month, and year. Never name tools to the caller — say “one moment, let me check” and continue once you have an answer. If you get no response: say the scheduling system isn’t reachable right now, take the preferred time as a message, and promise a callback.

That last point matters: without this rule, silence falls on the call whenever an interface is slow or down.

Examples

One short example dialogue per call reason — three or four lines, only the decisive turns. Without examples the agent interprets the flow differently each time. With too many long examples you burn your character limit for nothing.

Caller: “I need an appointment for a check-up, next week if possible.” Anna: “Of course. Would morning or afternoon suit you better?” Caller: “Morning.” Anna: “I have Tuesday at ten thirty or Thursday at nine. Which works better?”

What does not belong in the prompt

• No control characters, no formatting tags, no SSML. Expressions such as <emotion value="happy"/> or <break time="300ms"/> are read out literally — the caller hears them. Describe tone as an attitude (“calm, empathetic”) and pauses through sentence structure. If you inherited a prompt, check it for < and /> and remove everything of that kind.
• No instructions about speaking pace. That is a platform setting (Configuration → Show advanced), not a prompt instruction.
• No requests to sound “more human” or “more natural.” How it sounds comes from the platform and the voice. If you don’t like the sound: try a different voice, otherwise contact support.
• No notes to yourself. Change history, open questions, and to-dos cost characters and confuse the agent. Keep those separately — see Improving the Prompt.
• Nothing twice. Each rule exactly once. Contradictory repetition is the most common cause of unpredictable behavior.

Variables in the prompt

You can reference defined properties directly in the prompt — the syntax is ${propertyName}, e.g. ${firstName} or ${email}. The platform shows a hint about this in the editor. Use only this syntax; other bracket forms are not substituted and the agent reads them out.

If you exceed 10,000 characters

Cut in this order:

1. Move changing facts (hours, services, prices) into the Knowledge Base.
2. Reduce examples to one per call reason and shorten them to three or four lines.
3. Merge rules you have stated more than once.
4. Move rarely used call reasons into a second Workflow.

What you should not cut: response rules, the memory section, the facts rule, and pronunciation. Those sections carry the behavior.

Before / after

Bad — the typical first attempt:

You are a friendly assistant for Dr. Miller Dental Practice. Help callers with all their needs, be nice and human, use filler words so it sounds real. Book appointments and answer questions about prices and opening hours. Don’t be too long.

Why it fails: no flow (the agent improvises every call differently), no response length (“not too long” is not a rule), no memory rule (asks names twice), no facts rule (invents prices), no transfer (gets stuck on everything), no pronunciation (reads numbers wrong), plus an instruction about how it should sound, which doesn’t belong here.

Good — the same scenario along the sections above: persona in two sentences, then response rules, memory block, language, conversation management, three named call reasons with numbered flows, the facts rule referencing the stored documents, pronunciation rules, a transfer rule, and one short example per call reason. Length: one to two pages. The result isn’t more creative — it is repeatable, and only that can be improved.

Continue to Pronunciation.