When you write Facebook and Instagram ad copy with ChatGPT or Claude, do not just say "create an ad". Instead, give it one offer with checked facts and ask for several variants from different angles: the problem, the benefit, the proof and the most common doubt. The AI can suggest drafts at the length you set, but you need to recount the characters, and you are the one who checks whether the claims are true, whether the text sounds natural and whether it breaks Meta's policies. And only a test shows which variant is best.
This article is for a small business that runs its own ads in Meta Ads Manager. It is about manual work: you copy information into a chat AI tool and move the result into the ad. Meta's own built-in AI features are covered separately below.
- 1The offer and provable factsPlus the most common customer doubts
- 24 variants from different anglesChatGPT / ClaudeProblem, benefit, proof, doubt
- 3Check: language, claims, Meta policies, length
- 4Ads with your own copyMeta Ads Manager
- 5A/B test: results pick the winner
What are the three text fields in a Meta ad, and how long should they be?
A standard Meta ad with an image or video has three text fields. Primary text is shown above the visual: this is the main message. The headline is a short line below the visual, next to the call-to-action button. The description is an extra line below the headline, and it is not shown in every placement.
| Field | Meta recommendation | Note |
|---|---|---|
| Primary text | 50–150 characters | Facebook Feed with an image |
| Primary text | up to 125 characters | Instagram Stories |
| Headline | up to 27 characters | Facebook Feed with an image |
| Description | no specific number | may not be shown |
These are recommendations from Meta's Ads Guide, not hard limits (checked October 22, 2026). You can enter longer text, but on a phone part of it may stay hidden. So the main idea has to fit into the first sentence. The description is not shown everywhere, so put in it only what the ad can do without. Recommendations differ slightly for other formats (carousel, video), so check the page for your format in the Meta Ads Guide.
Lithuanian words are long, so a 27-character headline is three or four words. It is worth telling the AI tool this too: it prefers to write longer than needed.
Example: one offer, four ad variants
Say there is an upholstery cleaning service in Kaunas (Lithuania's second-largest city): it comes to your home and cleans a sofa or armchairs. The ad targets people in and around Kaunas, and the goal is bookings through the registration form on the website. All the facts used below are made up and only show what kind of facts you need: cleaning a three-seater sofa costs from €45, you can book a time online, the service has been running for 4 years, reviews are published on Google, and before cleaning the fabric is checked and the customer is told what to expect.
An angle is where the ad starts talking from. The same service can be presented in four ways:
- Problem. Starting from a situation the person recognizes: a stain on the sofa, a smell, guests coming at the weekend.
- Benefit. Starting from what the person gets: no need to take the furniture anywhere, you choose the time online.
- Proof. Starting from why they should believe you: reviews, experience, warranty, but only if they are real.
- Doubt. Starting from the most common reason not to book: "what if the stain does not come out", "what if the sofa stays wet".
Different angles suit different people: one responds to the problem, for another the main thing is not wasting time. Which angle works for your audience, neither you nor the AI knows in advance.
What to prepare before writing the prompt
AI writes convincingly even when facts are missing, and it may add facts you did not give it, or wrong ones. So before you open ChatGPT or Claude, write down:
- The offer in one sentence. What, for whom, where, for how much. E.g.: "Upholstery cleaning in your home in Kaunas, from €45 for a three-seater sofa."
- Facts you can prove. How many years you have been working, how many reviews and where they can be seen, whether you give a warranty and on what terms, how long the furniture takes to dry.
- The most common customer questions. Write down what people ask by phone or in messages: this is the best material for the doubt angle.
- What you must not promise. E.g. "every stain will come out", if that is not true.
- The landing page text. Prices, terms and the button must match the ad.
Do not paste customer names, phone numbers or extracts from conversations into AI tools. If you want to use reviews, rewrite their point without personal data.
A prompt you can copy
Paste it into ChatGPT or Claude and replace the parts in square brackets with your own information. General principles of good prompts are covered separately (How to write AI prompts). The original prompt asks for natural Lithuanian; replace it with the language your ads run in.
You are an experienced Lithuanian-language copywriter who writes Facebook and Instagram ads for small businesses. Offer: [one sentence]. Audience: [who, where]. Ad goal: [e.g. registration on the website]. Facts that may be used: [list]. What must not be promised: [list]. Most common customer doubts: [list]. Write 4 ad variants, one for each angle: problem, benefit, proof, doubt. For each variant give: primary text up to 150 characters (the main idea in the first sentence), a headline up to 27 characters, a description up to 30 characters that is not needed to understand the ad. Rules: use only the facts provided; if an angle lacks facts, say so instead of making something up. Do not ask the reader about their health, financial situation, age, religion or other personal attributes, and do not write as if you knew them. No strings of exclamation marks, no words like 'best' or 'guaranteed' unless they are in the facts. Write natural Lithuanian, the way a person would speak, not a translation from English. Under each variant, give the character count for each field and which fact each claim is based on.
Asking which fact each claim is based on makes checking much easier: you see straight away where the AI "added something of its own". Do not trust the character count at all: language models count inaccurately. Check the final length in the Ads Manager preview or in any character counter.
What the result could look like
This is how an edited AI answer could look for our example (the numbers are illustrative). The original copy was in Lithuanian; it is shown here in English.
| Angle | Primary text | Headline |
|---|---|---|
| Problem | A stain on the sofa after weekend guests? We come to your home in Kaunas and clean the fabric on the spot, no need to move the furniture. | Sofa cleaning at home |
| Benefit | We clean in your home, and you choose a convenient time online in a few minutes. Three-seater sofa from €45. | Choose your time online |
| Proof | We have been cleaning upholstery in Kaunas for 4 years. See what customers say in our Google reviews. | 4 years in Kaunas |
| Doubt | Worried the fabric will get damaged? We check it before cleaning and tell you what to expect before we start. | Fabric check comes first |
The same description works for all variants: "From €45". An example of a possible mistake: the doubt variant could start with "Allergic to dust mites?". That sentence should be deleted; the reason is explained below.
How to check ad copy written by AI
- Does it sound natural? Read it out loud. Common AI mistakes in Lithuanian copy: word-for-word translations ("unlock cleanliness"), English punctuation rhythm, too many adjectives, the formal "you" ("Jūs") capitalized in one place and lowercase in another. If you would not say the sentence to a customer on the phone, rewrite it.
- Can you prove every claim? "4 years", "from €45", "dries in a day": all of this must be true today. Meta's Advertising Standards prohibit deceptive or exaggerated claims about the results of a product or service, and especially about health benefits.
- Are there no personal attributes? In Meta ads you may not assert or imply that you know the viewer's personal attributes: race, ethnicity, religion, beliefs, age, sexual orientation, gender identity, disability, physical or mental health, financial hardship, criminal record or even their name. So "Allergic to dust mites?" or "Struggling to pay off your loan?" are risky sentences. Addressing the reader as "you" is fine if it is not linked to such an attribute: "A stain on the sofa?" works, because it is about the sofa, not the person.
- Does it match the landing page? If the ad says "from €45" and the page shows the price only after registration, the person is left unsure whether the offer is real, and trust may drop. How to compare the ad and the page systematically is covered separately (Does your ad match the landing page? Check it with ChatGPT or Claude).
- Does the text fit the visual? The primary text and the image should not repeat each other word for word, but they should tell the same story. How to prepare an ad image with AI is covered in a separate article (Ad images with AI).
Meta built-in AI features for ad text
Meta Ads Manager also has its own AI tools, grouped under the name Advantage+ creative. For text, Meta can generate variations of your primary text and headline, and some automatic enhancements can rewrite your text or move it between fields (checked October 22, 2026).
What matters. Meta says some enhancements may be turned on by default, but you can turn any of them off. Meta itself recommends reviewing and approving ad previews before launch, but notes that the preview shows only examples of possible versions, not all of them. Which features are available to you, and whether they work well with Lithuanian, depends on the account and format, so check in your own Ads Manager.
Practical conclusion: if precise claims matter for your service (price, timelines, warranty terms), it is better to turn off text generation and enhancements and use only your own checked variants. If the risk is low, you can leave them on, but review how the ad looks from time to time.
A third route is to connect a chat AI with the ad account technically (through the API or automation tools such as n8n). It is possible, but for a small business manual work is usually enough.
A variant is not a winner yet: how to test Facebook ad copy
Copy written by AI is a hypothesis. However convincing it looks, only the ad results show which one people choose. A few principles worth following:
- Test angles, not commas. Problem versus benefit is a real difference. Two almost identical sentences will not show a difference on a small budget.
- Change one thing. Meta's A/B testing tool is meant to compare two versions that differ in one variable, e.g. only the text, while the visual, audience and budget stay the same. The Meta Help Center advises against changing several things at once, otherwise you will not know what drove the result.
- Judge by the goal, not by clicks. CTR (click-through rate: what percentage of people who saw the ad clicked it) shows whether the text caught attention, but not whether it brought a customer. If the goal is registrations, look at registrations and their cost. For this, registrations must be measured correctly (Meta Pixel or Conversions API).
- Do not stop too early. After a day or a few dozen clicks, differences are usually random. Give the test a time and budget set in advance. In A/B test results Meta shows how likely it is that the winner would stay the same if the test were repeated; if this figure is low, the result is still unclear.
- 1Two ads, only the text differsVisual, audience, budget stay the same
- 2Time and budget set in advanceMeta A/B test
- 3Judge registrations and their cost, not CTRNeeds a working Meta Pixel or Conversions API
- 4A winner only if the result is reliable
- Take context into account. Holidays, weekends, price changes, a website outage during the test: all of these distort results more than the text does.
If you use Meta's text generation, remember: reports will not always show exactly which text version a particular person saw, so for a clean comparison of angles, separate ads with your own copy are more convenient.
The same offer for Google and Meta ads
In Google Search, the person types what they are looking for themselves: "sofa cleaning Kaunas". The ad answers a need that already exists, so the copy should repeat the search words and quickly state the price, location and next step.
On Facebook and Instagram, the person is not looking for anything: they are scrolling through friends' posts. The ad interrupts here, so it first has to catch attention with the visual and the first sentence, and it often has to remind people of the need ("guests at the weekend, and the sofa…"). The problem and doubt angles often matter more in Meta ads than in search.
In practice: you can use the same list of facts for both platforms; only the task for the AI tool changes. How to adapt the prompt to Google Ads and its character limits is covered in a separate article (Google Ads copy with AI).
Common mistakes
Letting the AI make up facts. "More than 1,000 happy customers" turns up in the text if you do not forbid it. Always ask which fact each claim is based on.
Launching ten variants at once on a small budget. The budget gets spread thin, and no variant collects enough data for a conclusion. Two or three different angles are better.
Questions about the person, not the situation. The personal attributes rule is most often broken by accident, with questions about health, finances or age. Rework the sentence so it talks about the product or the situation.
One text for every placement. Long primary text that looks good on a computer may be cut off in Stories. Preview the ad in every placement.
Sources
Meta Ads Guide: image ad in Facebook Feed: primary text (50–150 characters) and headline (27 characters) recommendations.
Meta Ads Guide: Instagram Stories: primary text recommendation for the Stories format.
Meta Advantage+ creative: AI features, limits of previews, default settings and turning them off.
Meta: text generation in Ads Manager: generating text variations from your primary text.
Meta Advertising Standards: privacy violations and personal attributes: the list of personal attributes and what is allowed.
Meta Advertising Standards: unacceptable business practices: the ban on deceptive or exaggerated claims.
Meta: About A/B testing: the one-variable principle and evaluating test results.