How to Write a Good AI Prompt

Updated January 2026 · 6 min read

Most prompts fail for the same reason: they're vague. "Write me an email" gets a generic reply. "Write a cold email to a SaaS founder about my design service, friendly but not pushy, under 100 words" gets something you can actually use.

This guide shows you the pattern behind the second kind of prompt, with before/after examples you can copy today.

The 4-part formula

Every strong prompt answers four questions:

1. Role — who should the AI act as?
2. Context — what's the situation?
3. Task — what exactly do you want done?
4. Format — what should the output look like?

You don't need all four every time, but skipping any of them lets the AI fill in the blank with its own guess.

Example — email to a client

The second version takes 15 extra seconds to write but saves you three rounds of "no, not like that".

Three mistakes that kill prompts

1. Vague audience

"Write an article about productivity" is fine for a school essay. For a blog post aimed at busy startup founders, you need to say so. The AI tailors vocabulary, examples, and tone based on who you name.

2. No format spec

If you don't say "bullet points" or "three paragraphs" or "one sentence", the AI picks whatever feels natural. Sometimes that's fine. Sometimes you wanted a table.

3. Missing constraints

Word limits, tone, things to avoid, facts it must not invent — all of these are constraints. Without them, the AI has infinite freedom and will exercise it.

A 30-second trick: the who-what-why filter

Before sending any prompt, ask yourself:

• Who is this for?
• What do I actually want back?
• Why — what's the goal or context?

If any of the three is missing from your prompt, add it. That alone fixes most prompt problems.

Different tools, slightly different tips

ChatGPT handles conversational instructions well but benefits from an explicit role. Claude responds better to structured instructions, sometimes with XML-like tags. Gemini likes factual precision and clear deliverables. If you use Epromptly, you can pick a target and it adapts automatically.

You don't have to write it perfectly

You'll get better at this with practice. But if you want a shortcut: paste your rough idea into Epromptly, choose a target and style, and let it rewrite your prompt for you. It's free.