Why tone makes all the difference
Imagine you need to cancel on someone. First it's your boss, then your best friend, and then your landlord. The message is always the same: you can't make it on Friday. But the tone? Completely different. You write to your boss: "I regret to inform you that I will be unavailable on Friday." To your friend: "Hey, can't do Friday, sorry!" And to your landlord: "Dear Mr. Miller, I'm afraid I need to reschedule our Friday appointment."
Three times the same information. Three completely different tones. And you do this automatically, without thinking about it. You adjust your style to the situation, the person, the context. It's a skill you've been practicing since childhood.
AI can do exactly the same thing. But only if you tell it to. By default, AI chooses a neutral, rather factual tone. Not bad, but not always the right fit. The good news: with just a few words in your prompt, you decide how the AI sounds. Formal or casual, friendly or matter-of-fact, humorous or serious. That's exactly what this article is about.
Five tones you should know
"Tone" might sound like something from music class, but it's really quite simple: it's about how a text sounds. Not what it says, but how it says it. Think of a radio station. Some sound serious like the evening news, others relaxed like a morning show. The content might be similar, but the feeling is completely different.
For your work with AI, five tones are particularly important:
Formal: Professional, polite, measured. Perfect for official letters, job applications, business correspondence, or communication with authorities. The AI will use phrases like "Dear Sir or Madam" and avoid any colloquial language.
Casual: Relaxed, conversational, approachable. Ideal for social media posts, internal team messages, or personal blogs. Here the AI can use abbreviations, contractions, and throw in a relaxed comment or two.
Friendly: Warm, inviting, positive. Great for customer letters, invitations, or newsletters. The tone isn't as distant as formal, but more professional than casual. Think of a nice colleague who's helping you out.
Factual: Neutral, fact-based, clear. Perfect for reports, summaries, instructions, or technical documentation. No emotions, no opinions, just facts and clear statements.
Humorous: Witty, entertaining, with a wink. Suitable for entertainment content, relaxed presentations, or creative pieces. Here the AI gets to use wordplay and surprise you.
How do you tell the AI which tone to hit? Directly. A simple addition to your prompt is all it takes:
- "Write in a formal tone."
- "Keep it casual and conversational."
- "Make the text factual and neutral."
- "Write in a friendly and inviting way."
- "Be humorous, but not silly."
That's it. No secret knowledge, no technical jargon. You tell the AI how to sound, and it does it.
Writing for your audience: who is the text for?
Now it gets interesting. Because tone alone isn't always enough. You also need to tell the AI who the text is for. A text about retirement planning sounds different when it's aimed at career starters than when it's written for people approaching retirement. A recipe for cooking beginners needs different explanations than one for experienced home cooks.
This is where the target audience comes in. And AI can distinguish between different audiences remarkably well, as long as you give it the right clues.
Here's an example: you want a text about data security. Without specifying an audience, you'll get a generic, rather dry text. But try these variations:
- "Explain data security for elementary school children. Simple, with examples from their everyday life."
- "Explain data security for small business owners. Practical, with concrete steps they can implement right away."
- "Explain data security for IT professionals. Technically precise, referencing current standards."
Three completely different texts. Same topic, different language, different level of detail, different examples. The rule of thumb is: the more you tell the AI about the target audience, the better the result fits. Age, prior knowledge, profession, interests - all of this helps the AI hit the right tone.
I know a tradesman who uses AI to write his quotes and proposals. In the beginning, they sounded like a lawyer had written them. Since he started adding "for private customers who have no technical background, in a friendly and easy-to-understand tone" to his prompts, he gets texts his customers actually understand while still sounding professional.
Technical language vs. plain language: when to use which
Closely related to the target audience is the question: how complex should the language be? This is one of the most common stumbling blocks when working with AI. Many people get texts back that are technically correct but sound either too complicated or too simple.
Let me paint a picture. Imagine a doctor explaining your diagnosis. If they say: "You have acute pharyngitis with accompanying rhinosinusitis," you probably understand nothing. If they say instead: "You have a sore throat and your sinuses are irritated too," you immediately know what's going on. Both statements are correct. But only one is actually helpful to you.
You can give the AI exactly this kind of direction:
- "Explain this in plain language, without technical terms."
- "Use technical terminology, but explain each term when it first appears."
- "Write at the level of a professional article for industry experts."
The middle option is especially useful: use technical terms, but explain them. This way a text sounds professional while remaining understandable. That's exactly what we do in this article series too. You learn terms like "prompt" or "tone," but always with an explanation in everyday language.
A practical tip: if you're unsure, just ask the AI for both versions. "Write this paragraph once in technical language and once in plain language." That way you can compare and choose the version that fits best. You can't break anything, so just try it out.
Style in action: job application, WhatsApp, and business proposal
Let's walk through this with three concrete examples. Imagine you want to tell someone that you successfully completed a project. Same content, three completely different situations.
The job application:
"In my role at Company XY, I independently led a digitization project that was successfully completed within six months. I was responsible for both project planning and coordination of the five-person team."
The WhatsApp message:
"Hey, guess what! The project is done! Six months of stress, but we made it. So proud right now. Celebrating tonight!"
The business proposal:
"We are pleased to inform you that we have successfully completed the digitization project on schedule. We would be happy to discuss the next steps with you in a personal meeting."
Three texts, one piece of information. The difference lies in the tone, the word choice, the structure. And you can control all of this in your prompts. Here are the matching prompts for each version:
For the job application: "Formulate the following for a job application cover letter. Formal tone, professional language, focus on my competencies: I led a digitization project to successful completion in six months."
For WhatsApp: "Write this as a casual WhatsApp message to a good friend. Colloquial, short, enthusiastic: I successfully completed my project."
For the business proposal: "Formulate this as a professional message to a business client. Polite, factual, with an outlook on next steps: The digitization project has been successfully completed."
You see: the magic isn't in complicated techniques. It's enough to clearly tell the AI who the audience is and what style to use. That's all it takes.
The creative option: when you want something different
So far we've talked about "standard tones." But what if you need something special? A text that sounds like a fairy tale? A product description in the style of a sports commentator? An invitation that starts like a crime thriller?
This is where the creative side of AI comes into play. And this is where it gets really fun.
You can give the AI practically any style. The more unusual, the more surprising the results. Here are some ideas:
- "Explain the topic of tax returns in the style of a soccer commentator."
- "Write an invitation to a team meeting as if it were a trailer for an action movie."
- "Describe our company product as if it were a fairy tale for children."
- "Write these safety instructions in the style of a pirate captain."
Sounds crazy? It is. But exactly these creative approaches can be worth their weight in gold in certain situations. A humorous safety notice is more likely to be read than a dry one. A team meeting invitation with a playful twist creates a better mood. And an explainer video in an unusual style sticks in people's minds.
The prompt generator on optiprompt.io has the creative variant specifically for this. It encourages the AI to think outside the box and take unconventional paths. So the next time you need a text that stands out from the crowd, try the creative variant. You'll be surprised.
A real-world example: an accountant I know sends a monthly reminder about outstanding invoices. It used to be a dry standard text. Since she started using the creative variant, the AI writes her rotating, humorous payment reminders. The result? Customers pay faster and complain less. Tone really does make the difference.
Hands-on exercise: one topic, three tones
Now it's time to get practical. In this exercise, you'll have the AI write the same content in three different tones. This way you'll experience firsthand how powerful the "tone" tool really is.
Step 1: Open the prompt generator
Go to optiprompt.io and select the category LLM and the variant Creative.
Step 2: Enter your content
Type something like: "Write a short message (about five sentences) welcoming a new team member."
Step 3: Have the AI create three versions
Copy the generated prompt into an AI tool of your choice (ChatGPT, Claude, or any other). Add the following instruction before the prompt: "Write this welcome message in three versions: 1. Formal and professional. 2. Casual and friendly. 3. Humorous and creative."
Step 4: Compare the results
Pay attention to these points:
- Which words change between the versions?
- How does the sentence length differ?
- Which version would you use in your workplace?
- Which version surprises you the most?
Bonus challenge: Try it with a different topic from your everyday life. Maybe a scheduling cancellation, a product description, or a birthday message. The more you experiment with different tones, the better your feel for it will become.
Conclusion: your text, your tone, your style
You now know that AI doesn't just have one voice - it has as many as you need. You can steer the tone from formal to humorous, tailor texts to specific audiences, and switch between technical jargon and plain language. You've seen how the same content can sound as a job application, a WhatsApp message, or a business proposal. And you know about the creative variant for texts that break the mold.
In the next article "Planning Trips with AI: From Weekend Getaway to World Travel," we'll show you how to apply what you've learned in a very concrete use case. You'll see: tone and style aren't just theory - they make a real difference in practice.
Until then: experiment with different tones. Have the AI write the same text in five different styles. Surprise yourself. Because the better you control the tone, the more useful AI becomes in your everyday life.
Your text, your tone, your style. The AI plays along.