How to Write a Brand Voice Guide So AI Replies Sound Like Your Business

A customer writes "kak, ready ga yang hitam?" and the AI replies, "Dear valued customer, thank you for reaching out to us. We are delighted to inform you that the item is available." The information is right. Everything else is wrong. The reply sounds like a bank letter, and the customer now knows they are talking to a machine that does not know your shop. A short brand voice guide prevents this.

Why voice matters in chat

• Recognition. Regular customers know how your shop talks. A sudden change in tone feels like a different business.
• Trust. A reply that matches how they wrote feels attentive. A stiff reply feels automated.
• Speed. Short, natural messages are read and answered faster.
• Consistency. Three admins and one AI should sound like one business.

What a voice guide contains

One page, seven parts.

1. Who you are, in one sentence

"A neighbourhood coffee roaster. We talk like a friendly barista who knows the beans well."

This sentence sets the direction for everything else.

2. How you address customers

Be explicit, because this is where AI most often goes wrong.

• What you call the customer: "Kak", "Bapak/Ibu", first name, "you".
• What you call yourself: "kami", "saya", "aku", the admin's name.
• When to switch: more formal for business buyers, relaxed for regulars.

3. Formality and warmth

Choose a point on each scale and describe it:

• Formal to casual.
• Serious to playful.
• Brief to detailed.

For example: "Casual and warm, never slangy. One emoji at most, and only in greetings or thanks."

4. Message shape

• Typical length: one to three short sentences.
• One idea per message, sent as separate bubbles, or one compact message.
• Lists only when comparing options.
• Always end with a question or a clear next step.

5. Words to use and to avoid

Use: the terms your customers use for your products, your standard phrases for price, stock and delivery.

Avoid: corporate filler such as "valued customer" and "we are delighted to inform you", exaggerated claims, technical jargon and anything you would not say across a counter.

A banned list is surprisingly effective. Five to ten phrases is enough.

6. How to handle specific moments

• Greeting a new customer and a returning one.
• Not knowing the answer: say so and pass to a person.
• Saying no: out of stock, outside the delivery area, cannot discount.
• Complaints: acknowledge first, no defence, hand to a person.
• Closing: how you thank and sign off.

7. Examples

The most important part. Five to ten real exchanges, each showing a customer message and the reply you would be proud of.

Customer: "Ready ga yang 250 gram?"

Reply: "Ready, Kak. Yang 250 gram Rp 85.000. Mau digiling atau biji utuh?"

Customer: "Bisa kirim hari ini?"

Reply: "Bisa kalau pesan sebelum jam 2 siang, Kak. Alamatnya di daerah mana?"

Models imitate examples far more reliably than they follow descriptions.

How to find your voice

If you have never written it down, the voice already exists in your chat history.

1. Collect twenty to thirty real replies that you think were good.
2. Note what they have in common: greeting, length, typical phrases.
3. Collect five replies you did not like, and note why.
4. Turn the patterns into the rules above.
5. Keep the best ten as examples.

Ask your longest-serving admin to review it. They usually know the voice better than the owner.

Testing the guide

Before going live:

• Give the AI twenty real customer messages and read the replies aloud.
• Check each against the guide. Does it sound like you? Is it the right length?
• Include difficult ones: an angry message, a vague one, a request the AI should refuse.
• Adjust the rules and examples, then test again.

A reply can be factually perfect and still wrong for your brand. Test both.

Keeping accuracy and voice separate

Voice is how you say something. Facts are what you say. Keep them in different places:

• Knowledge base: prices, stock rules, policies, opening hours.
• Voice guide: tone, wording, structure.

When the price changes, you update the knowledge base. The voice stays the same. Mixing the two leads to a guide that goes out of date every week.

Languages and code-switching

Many customers mix languages or use informal spelling. Tell the AI what to do:

• Reply in the language the customer used.
• Understand informal spelling and reply in clear, correct wording.
• Keep product names as they are.

For a business that serves both Indonesian and English speakers, write a few examples in each language.

Honesty in the voice

A good voice guide includes limits:

• Never claim to be a human.
• Never promise what the business has not approved: a delivery time, a discount, a refund.
• Never invent a reason or an excuse.
• Say "let me check with the team" when unsure, and actually hand over.

A friendly tone that makes false promises damages the brand faster than a stiff one.

Maintaining it

• Review the guide every few months, or when your customers or products change.
• Add an example whenever a reply needed heavy editing.
• Add to the banned list whenever a phrase slips through that makes you wince.
• Share it with human staff too. The guide should describe how everyone writes.

A short template

Who we are: [one sentence]

We call customers: [term]. We call ourselves: [term].

Tone: [three adjectives] and never [two things].

Length: [number] short sentences. End with a question or next step.

Use: [phrases]. Avoid: [phrases].

When unsure: say so and pass to a person.

Examples: [five to ten exchanges].

Polynusa lets you set the reply style for your workspace and learns from replies your team has sent, so that drafts from the AI assistant match how your business already writes. In Copilot it drafts for you to send. In Autopilot it sends within limits you set. See the pricing page.

Summary

Write one page: who you are, how you address customers, how formal and how long, words to use and avoid, how to handle hard moments and five to ten real examples. Build it from your own best replies, test it on real messages, keep facts in a separate knowledge base, and include the limits that keep the voice honest.

FAQ

Why do AI replies sound generic?

Without guidance, a language model produces a safe, neutral, slightly formal style. It is polite and it belongs to no one. Giving it specific rules and real examples of how your business writes replaces that default with your own voice.

How long should a brand voice guide for AI be?

One page. A handful of rules about greeting, formality, length and wording, plus five to ten example replies, works better than a long document. Examples carry more weight than descriptions, so spend your effort there.

Should the AI say that it is an AI?

It should never claim to be a human, and it should say plainly that it is an assistant when a customer asks. Many businesses also state it in the first message. Being open about it avoids a breach of trust later, and customers generally accept it when the answers are useful.