AI prompt: what it is, and how to write a good one

A prompt is the message you send to an AI to tell it what you want. If you have ever asked ChatGPT to "write an email to reschedule a meeting," you have already written a prompt.

On Index10, the prompt is how you create or change a site, an application, a screen, copy, or a user flow.

Do you need the perfect prompt?

No. The AI already understands a lot of your intent, and you can always fix things afterward: "change this," "add a contact section," "simplify the menu."

That said, two or three details upfront often change the first version: who it is for, what matters most, what tone. No need for a novel. Just enough to avoid something generic.

A somewhat vague example

Build me a beautiful app for my business.

A more useful example

I am a fitness coach. I want a simple app for my clients: account, weekly program, and messaging. Clear, motivating style.

You wrote nothing technical. The AI just has more to work with from the start.

A simple structure that works

When you start a project, think in four blocks (even short ones):

1. Identity: who you are / what this is
2. Audience: who it is for
3. Main action: what the person should be able to do
4. Feel: tone, style, references ("warm," "minimal," "premium but simple")

Then say what you are leaving out for the first version.

Prompts to start a project

A good starting point:

Create a site for [activity], aimed at [audience].
Goal: [get in touch / book / sign up / buy].
Pages: [home, about, offers, contact].
Tone: [professional / warm / premium].
Include a visible call to action on the home page.
Not yet: [shop / messaging / payments].

Then, once the base is there, you refine message by message.

Tip: have the AI improve your brief

Before building, you can ask:

Here is my idea: […]. Rewrite it as a clear brief to build a first version. Ask me 5 questions if something is missing. Then propose the first creation prompt.

You stay in control: the AI helps you clarify; it does not decide for you.

After a painful bug, another useful move:

Summarize the problem we just fixed and write an "anti-recurrence" prompt I can reuse next time.

Important details work best at the start and end of the message: that is often where the AI hooks best.

Build in pieces (often better)

Asking for "the whole site at once, perfect" often gives something generic and hard to fix.

Chain instead:

1. Home + navigation
2. One offer / product page
3. Form or main flow
4. Visual details
5. Accounts / data only if needed

Each piece gets tested before the next.

Real content beats placeholder text

Avoid "Lorem ipsum" and "Feature 1 / 2 / 3."
Give real words: your offer, indicative pricing, your promise.

The AI uses meaning to choose structure. Vague content produces a vague site.

Useful words for style (without jargon)

Instead of "make it modern," pick a direction:

• "Minimal, lots of space, few colors"
• "Warm, photos, conversational tone"
• "Serious B2B, short headlines, trust"
• "Bold, strong contrast, little text"

A mood reference helps ("like a calm design studio"), without asking to copy a site.

Prompts to fix things (often more important)

The best results rarely come from the first message. They come from adjustments.

Useful examples:

• "The home page headline is too generic. Replace it with: …"
• "On mobile, the menu is too crowded. Simplify it to 4 links."
• "Add an FAQ section with these 5 questions: …"
• "The form should ask for name, email, and message only."
• "Do not touch the other pages: change only the home banner."

Golden rule: one clear request at a time. If you ask for five changes in one message, the result gets harder to control.

Treat the AI like a motivated junior (not like Google)

It cannot read your mind. If you leave a gap, it fills it in.
Be concrete: form fields, tone, what should happen after a click, what not to touch.

What to avoid

• "Make it better" (better by what criteria?)
• "Modernize" (modern for whom?)
• "Add everything a SaaS needs" (too broad)
• Pasting a 40-line essay with no priorities
• Contradictory instructions ("ultra simple" + "every option on the market")
• Pasting service keys or real customer data in the chat

Instead, say what is wrong and what you want instead.

Prompt and vibe coding

In vibe coding, the prompt is your main tool. You are not assembling technical blocks: you are directing.

For the concept: What is vibe coding?
To speed up your practice: 10 tips to build faster with AI

Index10 tip

On Index10, the chat edits your project and you see the result in the live preview. Start with the user journey ("a visitor arrives, understands the offer, books"), not the tech.

If you need accounts, saved data, or files:

I need users to create an account and find their info again. Enable Index10 Cloud if it is not already on, then build this flow.

If a service key is needed (payment, email…): do not paste it in the chat. Ask instead:

Open the secure form to add this key in Cloud → Secrets.

You can also switch to Chat only mode (answers without editing the project) to clarify a plan, then go back to build mode. Visual mode lets you adjust elements by clicking in the preview.

And if something goes wrong: describe the symptom ("the button does nothing") rather than guessing the cause.

Mini library of useful prompts

Showcase site

Create a showcase site for [trade] in [city]. Highlight [3 benefits]. Add testimonials, simple pricing, and a contact form. Realistic copy, no fake Latin.

Internal tool

Create an internal tool for my team. We need to add tasks, assign them, and track status (to do / in progress / done). Simple interface, visible priorities.

Product MVP

Create an MVP for [idea]. One main function only: [action]. Skip advanced options for now. Then list what you deliberately left out.

Audit / fix

Walk through the project like a beginner user. List what is confusing or broken. Then fix the worst problem first.

The real secret: iterate

The first message starts things off. The next ones refine.
If the result is not perfect, that is fine: say what is off, in one sentence.

That is how most people move fast without obsessing over "the perfect prompt."