AI captions that sound like you: the brand voice system
An AI writes you ten Instagram captions in twenty seconds. The problem is not the speed — it is that all ten sound like nobody. Like friendly nothing, like an advertising agency idling, like the same twelve phrases you now recognise out of the corner of your eye.
The cause is rarely the model. It is that most people give the AI a task they would never give a new intern: “write something for Instagram” — without saying who the brand is, who it speaks to, and what it would never say.
This article does not offer another bundle of tips but a system in three parts: a profile that makes your voice describable, a prompt scaffold that uses it, and a check that keeps nonsense from going live. All of it copyable.
The short version
- Generic copy is a context problem, not a model problem. Without guidance every model writes the average of its training material — and that sounds like everyone.
- A six-field brand voice profile beats any “better prompt”. Built once, it applies to every post.
- The first 125 characters decide. After that Instagram truncates in the feed and shows “more”. Only people already interested read what follows.
- 2,200 characters is the limit, 30 hashtags the maximum. The 31st makes publishing fail — one of the most common causes of “the post won’t go out”.
- Hashtags no longer bring reach. They categorise. Search terms in the text now count for more than a cloud of hashes.
- The check stays human. Seven points, two minutes — the difference between saving time and issuing a correction.
Why AI captions sound generic
A language model predicts the most likely next word. Without constraints it inevitably lands in the middle: on the phrasings that appeared in millions of marketing texts. That is not a flaw, it is exactly how it works. If you do not want the average, you have to narrow the field.
Three things are almost always missing:
- Context — who the brand is, who is listening, what the post should achieve. Without it the AI writes for “everyone”, and “everyone” is nobody.
- Examples — two or three real texts of your own say more about a voice than ten adjectives. “Casual but professional” means something different to every person and even less to a model.
- Prohibitions — what must never appear. The most underrated part, and the one that works fastest.
The twelve phrases that give away AI copy instantly
These formulations are the visible residue of the average. They are not wrong, just worn out — and when three of them sit in one caption, readers stop without being able to say why:
- “In today’s fast-paced world …”
- “Dive into …”
- “And the best part?”
- “It’s more than a product — it’s a lifestyle.”
- “We all know that feeling when …”
- “Ready to take your business to the next level?”
- “Let’s do this together …”
- “Not only fast, but also sustainable.”
- “A real game changer.”
- “Made with love ✨”
- “Whether breakfast, lunch or dinner — with us you’ll find …”
- “Tell us in the comments! 👇”
The last one is the most interesting: asking for comments is not bad in itself — it is dead only when there is no question in front of it that anyone would seriously want to answer. “What is your Sunday breakfast?” works. “Tell us in the comments!” without a question does not.
These twelve lines belong first in your profile, in the “forbidden words” field. That alone lifts quality noticeably, before you have worked on anything else.
Your brand voice profile in six fields
The profile is the core. You fill it in once, store it, and hand it to every prompt. Six fields are enough — more will not be maintained:
- 1. Tone axes — three sliders instead of adjectives: sober ↔ playful, close ↔ distant, terse ↔ expansive. A value from 1 to 5 each. Numbers are unambiguous; “authentic” is not.
- 2. Address and person — informal or formal, we or I. Sounds trivial, but it is the most common inconsistency in company feeds.
- 3. Stop list — words and turns of phrase that never appear. The twelve above plus your own pet hates.
- 4. Sentence shape and emoji — maximum sentence length, whether questions are allowed, how many emoji (and which). “At most two, never in the first sentence” is a rule a model can follow.
- 5. Content pillars — three to five topics you actually talk about. This prevents posts that sound fine but have nothing to do with you.
- 6. Evidence instead of superlatives — what you say when you would otherwise write “the best”. For example: “in the same spot since 1998” instead of “steeped in tradition”.
Filled in, it looks like this
Example restaurant, South Tyrol:
Tone axes: sober/playful 3 · close/distant 2 · terse/expansive 2
Address: informal, we
Stop list: culinary journey, treat for the palate, moments of indulgence, made with love, dive in
Sentence shape: at most 15 words per sentence, questions allowed, at most one emoji, never in the first sentence
Content pillars: dish of the day · the people in the kitchen · producers from the valley · opening hours and occasions
Evidence: “The cheese comes from the farm 4 km up the hill” instead of “regional excellence”
This is not a brand bible and should not become one. It fits on half a page and takes twenty minutes to write — it never fails on difficulty, it simply never gets done.
The prompt scaffold to copy
A prompt that works has six blocks, in this order. Put your profile into block three and leave the rest as it is:
Role: You write Instagram captions for [brand], [what the brand does].
Context: The audience is [who]. This post shows [what happens in the image/video]. Goal of the post: [saves / a visit / a reply in the comments].
Voice: [your profile from the six fields, pasted verbatim]
Examples: Here are three captions of ours that hit the tone: [three real texts of your own]
Task: Write three variants. Each starts with a self-contained first sentence of at most 125 characters that makes sense on its own.
Limits: No prices, no opening hours, no claims about effect or origin that are not in the context. Invent nothing. No words from the stop list.
The most effective block is “Examples”. Three real texts move the result more than any pile of adjectives — the model then has something to align with instead of something to interpret.
The second most effective is “Limits”. A model does not invent opening hours out of malice but because it fills the gap. Forbid the filling and you get a blank instead — and a blank is caught during review.
Before and after: three examples
Restaurant
Without profile: “Dive into a culinary journey full of moments of indulgence! ✨ Our team conjures up dishes made with love from regional excellence every day. We look forward to seeing you! 🍽️”
With profile: “The cheese on today’s dumpling soup comes from the farm four kilometres up the hill. Martin brings it over himself on Tuesdays — which is why the soup is only on Tuesdays. From 11:30, while the pot lasts.”
What changed: one concrete detail instead of three superlatives. The second text cannot be copied onto another restaurant — that is the whole trick.
Online shop
Without profile: “Ready to take your style to the next level? Our new collection is more than fashion — it’s a lifestyle. Discover it now! 🔥”
With profile: “The jacket has two inner pockets, because our customers asked for pockets three times as often as for colours in the survey. We listened. Sizes 34 to 48, from Thursday.”
What changed: a decision is explained rather than asserted. It is also why texts like this get saved more often — they contain information, not a mood.
Coaching
Without profile: “We all know that feeling when the calendar overflows. Let’s work together to unlock your full potential! Tell us in the comments 👇”
With profile: “Three out of four first conversations start with the same sentence: ‘I actually know what I should be doing.’ The problem is rarely missing knowledge. It is the order. What has been sitting at the top of your list for weeks and still never gets done?”
What changed: an observation from their own work — something only this person could write. And the closing question can actually be answered.
Craft: what a caption has to carry
- The first 125 characters are everything. After that Instagram truncates in the feed and shows “more”. So the first sentence has to stand alone — as a statement, not as a run-up.
- 2,200 characters is the limit. Long captions are allowed and they work when the opening carries; they are no substitute for it.
- Structure: an opening that creates curiosity — substance in the middle — a single call to action at the end. Two calls to action are none.
- Search terms belong in the text, not in the hashes. Instagram search evaluates what you write; “breakfast in Bolzano” inside a sentence does more than the same term as a hashtag.
- Alt text describes the image for people who cannot see it — and is at the same time a signal about the subject. Two sentences are enough.
Hashtags: fewer, but right
The maximum is 30 per post — and the 31st makes publishing fail, one of the most common causes of posts that “just won’t go out”. What matters more is the effect: Instagram head Adam Mosseri has repeatedly stated publicly that hashtags are not a meaningful lever for reach; at the end of 2024 the ability to follow hashtags was removed as well. They categorise content, they do not distribute it.
The practical consequence: three to five precise hashtags that genuinely describe the subject — instead of thirty, twenty of which belong to topics that never appear in the post. Put the attention you save into the first sentence.
The seven-point check before posting
- Is every fact right? Prices, times, availability, names. Whatever the AI could not know, it has probably invented.
- Is there a stock phrase in there? Go through the stop list. One is enough to make the rest look suspect.
- Does the first sentence carry alone? Read only the first 125 characters. If nothing sticks after that, start again.
- Is there something only you could know? If not, the text could have come from any competitor.
- One call to action, and can it be answered? A real question beats any “comment now”.
- Alt text set? On images you can; on reels and stories you cannot — there the caption has to do that work too.
- Does anything need disclosure? Advertising, collaborations, realistic AI-generated images. When in doubt, disclose.