You type “write a Reels script for our dental clinic” and get back: “Scene 1. A dentist in a white coat smiles at the camera. Voiceover: ‘Hey guys! Today we’re going to talk about why taking care of your teeth is so important…’” Five scenes, three locations, a drone shot over the building, and 180 words of voiceover that won’t fit into 30 seconds even if you speed-read it.
The model isn’t broken. It did exactly what you asked: an average script for an average video. It doesn’t know you’ll be filming on a phone during lunch break, that the person on camera is the front-desk manager rather than the lead dentist, or that the first two seconds decide whether anyone watches the rest.
Below: what a short-video script is made of, the brief to give the AI, six prompts for Reels and Shorts, how to check a script before filming, and where AI gets it wrong every time.
Why “write me a Reels script” doesn’t work
Three reasons, all about context:
- No timing. Natural speech in a short video runs about 2.5 words per second, roughly 150 words a minute (test yourself with a timer). Thirty seconds is about 75 words, not half a page. The model won’t account for that unless you tell it.
- No constraints. Left alone, AI writes for a production studio: location changes, close-ups, actors. Your real resources are a phone, one person and 20 minutes.
- No single idea. “About our dental clinic” produces a video about everything at once. A short video holds one idea: “why your gums bleed when you brush” is a script; “dental health” is not.
Anatomy of a 30-second script
Ask the model for a table, not prose. That way you see what’s on screen, what the text says and what’s spoken:
| Time | On camera | On-screen text | Voice |
|---|---|---|---|
| 0–2 s | Close-up: toothbrush with pink foam | ”Bleeding when you brush — normal?” | — |
| 2–6 s | Dentist by the chair, looks at camera | ”No" | "No. And toothpaste alone won’t fix it” |
| 6–22 s | Three causes, one per shot | 3–5 words per cause | One sentence per cause |
| 22–28 s | Jaw model, correct brush angle | ”45° to the gum line" | "Here’s how to brush until you see us” |
| 28–30 s | Dentist holding the model | ”Book via link in bio" | "Bleeding for over a week? Come in” |
Rules worth putting in the prompt:
- The hook lives in the image and on-screen text, not just the voice. Many people watch with the sound off.
- On-screen text: 5–7 words at a time. Keep it out of the bottom fifth of the frame and away from the right edge — the caption and interface buttons sit there.
- No greetings. “Hey guys” is two seconds in which the viewer has already swiped.
- End on an action or a loop. Either one specific action, or a final shot that leads back to the first so the video gets a second watch.
Reels and Shorts can now run up to 3 minutes, but for scripts from these prompts aim for 20–45 seconds: a long video needs different editing and a different structure.
The brief: six points
Before any prompt comes the brief. Write it once and paste it at the start of every request:
- Who we are and for whom. “Dental clinic in Austin, South Lamar. Patients aged 25–45, they come in with acute pain or for cleanings.”
- Platform and length. “Instagram Reels, 30 seconds, vertical 9:16.”
- Who films and what’s available. “Phone, one dentist on camera, treatment room, jaw model. No drone, no location changes.”
- The one idea. “Bleeding when brushing is a reason to book a cleaning, not to switch toothpaste.”
- Voice. 2–3 examples of your best captions or video transcripts. How to pin that voice down is covered in the article on tone of voice.
- Don’ts. “No promises about treatment results, no prices, no ‘hey guys,’ no emoji in on-screen text.”
The brief takes 10 minutes, once. Without it, you’ll rewrite every answer the model gives you.
Six prompts for Reels and Shorts
Every prompt starts with the brief. Then the task.
1. Hook bank. “Give me 10 options for the first two seconds of a video on this topic. For each: what’s on camera, on-screen text up to 7 words, and the first line. Hook types: mistake, number, warning, question, before/after. Mark the three strongest and explain why.” Hooks are cheaper to generate in bulk and pick by eye. For topic ideas by niche, see our list of Reels ideas.
2. Script as a table. “Write a 30-second script as a table: time, on camera, on-screen text, voice. Voice: no more than 75 words. Only what can be filmed on a phone in one room.”
3. From post to videos. “Here’s our post: [text]. Turn it into three scripts of 20–30 seconds, each about one idea from the post. Don’t retell the whole post.” One breakdown becomes a series — the method is covered in detail in the article on content repurposing.
4. Faceless. “Rewrite the script so only hands and process are on camera and the meaning comes through on-screen text. No voice; sound is the work itself and quiet background.” Good for workshops, bakeries, repair services.
5. Critic. “You’re a viewer scrolling on the subway. Go through the script second by second and mark where you’d swipe and why. Then suggest edits only for those spots.” This prompt is more useful than three more scripts.
6. Platform versions. “Adapt the script: for Reels, a caption with the search phrase in the first line; for Shorts, a title up to 100 characters with the search phrase first and two lines of description.” On Shorts the title works for search; Reels has no title at all — the difference is covered in YouTube Shorts for business.
A five-minute check before filming
- Read the voiceover aloud with a timer. If a 30-second script takes 40 seconds to read, cut text — don’t talk faster.
- Mute it in your head. By second three, is it clear from the image and on-screen text what the video is about?
- One idea. Two ideas in a script means two videos.
- Check the facts. Numbers, timelines, prices and medical claims may be made up. Anything that sounds like a fact gets checked against your own documents.
- Test it. Instagram has trial Reels, which are shown to non-followers first. Film two hooks for the same video and compare which one gets fewer swipes.
Where AI gets it wrong every time
- Trends and sounds. The model can’t see today’s feed and will confidently recommend a “trending sound” that peaked long ago. Pick sounds in the app itself.
- Humor and slang. Jokes come out bland or sound like they were written for a different country. Local references are the weakest spot.
- Impossible shots. “A smooth camera glide through the clinic” without a gimbal looks like it was filmed during an earthquake. Ask for static shots and handheld only.
- Promises. “A perfect smile in one visit” is exactly what a model will write, and exactly what gets a clinic into trouble.
- Realistic AI video. If AI generated the video itself rather than just the script, Meta, YouTube and TikTok require you to label realistic synthetic content.
When this won’t work
- Nobody to film. A script doesn’t turn into a video by itself. If no one on the team can spend an hour a week with a phone, start with carousels.
- Nothing to show. A complex B2B product with no visual side is better explained in text and webinars than in 30-second clips.
- Expecting virality from a prompt. A prompt saves time on the draft, but it doesn’t replace knowing your audience: the questions customers ask and what annoys them.
A good short script is 10 minutes with the model and 5 minutes of editing. After that comes routine: edit, publish to Reels and Shorts at different times, see what worked. In Repost21, videos go out to Instagram and YouTube on schedule from one calendar, and analytics for both accounts sit on one screen. Try it free.