How to write a prompt for a product description

A good prompt is mostly rules and facts. The clever phrasing matters far less than telling the tool what it may and may not say.

OpenAI describes prompt engineering as writing effective instructions for a model, so that it consistently generates content that meets your requirements.¹ The same guide says the content a model generates is non-deterministic, so you shouldn't expect the same answer every run.¹ Expect to read every draft.

A layout that works

OpenAI's guide suggests a developer message with sections in a usual order: a description of the purpose and style, instructions, examples, then context.¹ Chat tools aren't built the same way, but the order carries over. Here's how it maps to a product description.

Purpose and tone. One or two sentences. Who reads the page, and how should it sound? "You write product descriptions for a small online shop. The tone is plain and friendly. Use Australian spelling."

Rules. The guide asks what rules the model should follow, what it should do and what it should never do.¹ For this job the rules are mostly "never":

• Use only the facts in the fact sheet.
• If a detail isn't in the fact sheet, leave it out. Don't estimate.
• Don't claim health, safety or environmental benefits.
• Don't use words like "perfect", "ultimate" or "must-have".
• Write short sentences and no more than the length you set.

An example. The guide wants example inputs paired with the output you'd like back.¹ Paste one fact sheet and the description you approved for it.

This product's facts. Last, paste the new fact sheet. The guide calls this context, and it usually sits near the end of the prompt.¹

Why "leave it out" matters

The ACCC's list of things a business shouldn't do begins with guessing the facts and includes making vague or unclear claims.² A prompt that says "write something compelling" invites both. A prompt that says "use only these facts" doesn't.

A prompt you can adapt

You write product descriptions for a small online shop. The tone is plain and friendly, with Australian spelling.

Rules: use only the facts below. If something isn't listed, don't mention it. No claims about health, safety, the environment or results. No superlatives. Two short paragraphs and a bullet list of specifications.

Example fact sheet and approved description: [paste]

Facts for this product: [paste]

Swap the spelling and tone for your own market.

Ask for the gaps

Add one more line: "After the description, list any fact you needed but weren't given." The tool then tells you what's missing instead of burying a guess in the copy. It won't always do this correctly, so your own fact sheet stays the reference.

Change one thing at a time

If a draft is wrong, work out why. Was a fact missing? Was a rule unclear? Edit the prompt, not just the draft, so the fix applies next time. Keep a copy of the prompt that works. The voice page explains how to build the tone part, and the checking page covers what to do with the draft once you have it.