Writing Good Prompts

Step 1: A prompt is a clear message

A model can only work with what you give it. A vague prompt gets a vague answer.

Compare:

• Weak: Volcanoes
• Better: Explain how volcanoes erupt.
• Best: You are a friendly science teacher. Explain how volcanoes erupt to a 9-year-old in 3 short sentences.

The best prompt tells the model who it is, what to do, for whom, and in what shape.

Step 2: Four parts of a strong prompt

You don’t always need all four. But when an answer disappoints you, ask yourself: which of the four did I forget?

Step 3: Show an example

Sometimes the easiest way to explain what you want is to show it. Adding a few examples is called few-shot prompting.

Turn each word into a simple definition for a child.

Word: planet
Definition: A huge ball of rock or gas that travels around a star.

Word: river
Definition: A long stream of fresh water that flows to the sea.

Word: volcano
Definition:

The model sees the pattern (word, then a one-line child-friendly definition) and continues it. Examples are especially good for style and format.

Step 4: Templates in Python

In an app you don’t type a new prompt every time. You write a template with blanks, and the program fills them in. Python’s f-strings are perfect for this.

def explain_prompt(topic, age):
    return (
        f"You are a friendly teacher. Explain {topic} "
        f"to a {age}-year-old in 3 short sentences."
    )

print(explain_prompt("rainbows", 8))
print(explain_prompt("electricity", 12))

You are a friendly teacher. Explain rainbows to a 8-year-old in 3 short sentences.
You are a friendly teacher. Explain electricity to a 12-year-old in 3 short sentences.

Good enough, but notice “a 8-year-old” should be “an 8-year-old”. Small details like this are why you test prompts and read the results.

You can keep many templates in a dictionary and pick one by name:

recipes = {
    "explain": "Explain {topic} to a {age}-year-old in 3 short sentences.",
    "quiz": "Write 3 quiz questions about {topic} for a {age}-year-old.",
}

def build_prompt(name, topic, age):
    return recipes[name].format(topic=topic, age=age)

print(build_prompt("quiz", "volcanoes", 10))

Write 3 quiz questions about volcanoes for a 10-year-old.

Step 5: Improve, test, check

Good prompts come from a loop:

1. Write a first version.
2. Test it with several different inputs, not just your favorite one.
3. Read the answers critically. Are they correct? Clear? Safe?
4. Improve the prompt and test again.

Safety rule: Never type personal information (full names, addresses, phone numbers, passwords) into an online AI tool. Treat anything you type as something that could be seen by others.