AI shopping assistants often don’t read your whole product description. Some write a shorter version of their own. Some just cut it off. Either way, the fact a shopper is deciding on has to be near the top, or it may not be there at all.
We saw this happen in our own test. When we built our product-picking simulation, we trimmed each listing’s description to about 215 characters, the way a catalog card would. Two real humidifiers on that shelf said they cover “up to 536 ft²”. In both descriptions, that number started just past our cut, at character 246 and character 267.
Our test shopper had a 450 sq ft bedroom. Both humidifiers were big enough and under her budget. And GPT-6.1-Sol kept telling her, correctly for what it could see, that “neither confirms 450 sq ft coverage.”
Nobody tells you where the cut is
There’s no published rule for how much of a description an AI assistant reads. Here’s what we do know:
- ChatGPT rewrites. OpenAI says ChatGPT may generate simplified product titles and descriptions to make results easier to read. It doesn’t say what it keeps.
- ChatGPT may also cut. Peec AI, a visibility-tracking company, reports that in debug data from US sessions, every description was cut at exactly 50 tokens when products were scored. That’s roughly 40 words, or about 250 characters.
- Shopify may rewrite first. Shopify marks the description in its catalog as “Inferred”, meaning it can be generated or enriched by Shopify before an assistant ever sees it.
So treat 250 characters as a working budget, not a law. If the deciding fact is in your first two sentences, it survives every version of this we know about.
Most descriptions put their numbers late
We went back to our snapshot of 162 shopper-style searches in Shopify’s catalog and measured every product description in it.
Most are long. Of 1,594 descriptions with any text, 1,458 ran past 250 characters. The median was about 1,000.
Length alone wouldn’t matter if the important part came first. It mostly doesn’t. Of the 760 descriptions that state at least one measurement with a unit (decibels, liters, hours, inches, pounds, square feet and so on), 542 don’t give the first one until after character 250. That’s about seven in ten.
On the humidifier shelf below, the openings read like headlines: “Cool Mist Humidifier for Large Rooms”, “Smart App & Voice Control”, “delivers visible cool mist through dual rotating nozzles”. The numbers come later, sometimes in paragraph three, sometimes in a spec list at the bottom.
What a 250-character cut does to a real shelf
Here’s the shelf from our humidifier search, “humidifier for dry winter air large room quiet top fill”. A shopper typing that wants two facts above all: how loud, and how big a room. This is what the top 10 descriptions said, and what’s left after 250 characters.
| Listing | Description length | Noise level | Room size | Left after 250 characters |
|---|---|---|---|---|
| 2nd | 174 characters | “21dB” at character 83 | “700ft²” at 31 | Both |
| 3rd | 1,182 | “26 dB” at 1,042 | “536 ft²” at 246 | Room size only |
| 4th | 948 | Words only: “runs quietly enough to leave on overnight” | “400 square feet” at 253 | Neither |
| 5th | 1,474 | “28dB” at 151 | Not stated | Noise only |
| 7th | 1,304 | “26 dB” at 980 | “536 ft²” at 267 | Neither |
The other five descriptions state neither number anywhere.
So in the full descriptions, 4 listings give a decibel figure and 4 give a room size. In the first 250 characters, 2 give each. Look at the 4th listing: the cut lands between “rated for single rooms up to” and “400 square feet”. Three characters cost it the one fact the shopper asked for.
The 7th listing has the hardest luck. It answers everything this shopper wants: 536 ft², 26 dB, up to 62 hours. But it spends its first 175 characters on “Powerful Cool Mist Humidifier for Large Rooms”, app and voice control, and the rooms it suits before it reaches a number.
Some of these numbers also appear in the spec lists Shopify generates for each product. That helps, but those lists are Shopify’s writing, not yours, and Shopify labels them as possibly missing or wrong. Don’t count on them to carry your best fact.
Write the first 250 characters on purpose
You don’t need a shorter description. You need a better first two sentences. Put these in, in this order:
- What it is, in plain words. “Cool-mist humidifier”, not “the Drift”. An assistant has to know what the thing is before any number means anything.
- The two or three numbers people buy on, with units and conditions. “26 dB on low” beats “26 dB”, and both beat “whisper quiet”.
- Who it’s for, or where it stops. “For rooms up to 536 ft²” answers the big-room shopper and politely turns away the warehouse.
- Then everything else. Your story, the materials, the warranty and the care instructions all keep their place, just lower down.
Here’s the 3rd listing’s own opening, then the same listing rewritten using only facts its full description already states:
Before (first 250 characters): “Cool Mist Humidifier for Large Rooms — 62H Runtime, Dishwasher Safe The [model name] delivers powerful, quiet humidification for bedrooms, nurseries, and large living spaces. With a 6.2 L top-fill tank and 320 ml/h mist output, it covers up to 536 …”
After: “Cool-mist humidifier for rooms up to 536 ft². 26 dB, 6.2 L top-fill tank, up to 62 hours per fill. Dishwasher-safe parts.”
The rewrite is about 120 characters. Nothing in it is new: the noise level was simply moved up from character 1,042. (If you know the setting the 26 dB was measured on, add it. The listing doesn’t say.)
Our guide to writing product descriptions for AI covers the full structure, including how to word an honest limit.
Check your own in five minutes
- Copy the description of your best seller from your Shopify admin.
- Paste it into any character counter and find character 250. That’s about 40 words.
- Write down the question customers ask most about this product, and the number that answers it.
- Is that number before the mark? If not, it’s the first thing to move.
- Make sure the product-level description isn’t empty. For a gift box from a small Canadian lip gloss brand, Shopify’s catalog showed a blank product description for about a week while the full text sat only on the variant. Any assistant reading the product description got nothing.
If you sell several versions of a product, do this on each one. Each version needs its own deciding numbers near the top, or an assistant may borrow them from a sibling.
How we checked
We stripped the HTML from every product description in our saved Shopify Catalog results for 162 searches (October 26, 2026, no shopper location set) and recorded where each one first stated a number with a unit. For the humidifier shelf we read the 10 descriptions by hand and recorded the character position of each noise level and room size. For the simulation story, we compared the 215-character snippets our models saw with the full saved descriptions, and re-read the models’ stated reasons. We re-read the OpenAI, Peec and Shopify pages on November 4, 2026.
Your next step
Take your best seller and its most-asked question. Find the number that answers it, and move it into the first sentence of the description, with its unit and the setting it was measured on. Then check the product in Shopify’s catalog again in a week to see what it carries now.