AI Letter Writing: Prompts, Examples, and What to Check

AI letter writing works well for one reason: most letters follow a known structure, and the hard part is not the structure but getting started and finding the right tone. A good AI draft gets you from a blank page to a solid first version in a minute. A bad one sounds like every other AI letter, gets a fact wrong, and makes the reader trust you less.

The difference is almost entirely in what you give the model and what you check afterwards. This guide covers a prompt framework that works for any letter, worked examples for the most common types, and the edits every AI-written letter needs before it goes out.

What AI is good and bad at in letters

Good at:

• Structure: opening, purpose, supporting points, request, close.
• Tone shifts: making a blunt note polite, or a rambling one firm.
• Length control: turning a page of notes into three tight paragraphs.
• Formal conventions: salutations, sign-offs, and the order of a business letter.
• Variations: giving you three openings to choose from.

Bad at:

• Facts it was not given. Ask for a complaint letter without the order number and it may invent one, or leave a vague placeholder you miss.
• Your real reasons. A cover letter that says you are “passionate about innovation” is the model filling a gap you left.
• Knowing the reader. It does not know your landlord is reasonable or your manager hates long emails unless you say so.
• Legal effect. A letter disputing a charge, resigning, or giving notice can have consequences. AI can draft it; it cannot tell you whether it does what you need legally.

The rule that follows: you supply every fact and the real goal, the AI supplies structure and wording, and you check the result.

A prompt framework for any letter

Every good letter prompt answers six questions. Leave one out and the model guesses.

1. Type and purpose. What kind of letter, and what should happen after it is read? “A complaint letter asking for a full refund”, not “a complaint letter”.
2. Sender and recipient. Who you are, who they are, and your relationship. A letter to a long-time client reads differently from one to a stranger.
3. The facts. Dates, amounts, order or account numbers, names, what happened in order. Paste them as a list.
4. Tone. Warm, neutral, firm, formal. Add a constraint if it helps: “firm but not angry”, “friendly but no exclamation marks”.
5. Length and format. “Under 200 words”, “three paragraphs”, “formal business letter format with addresses”, “plain email”.
6. What to avoid. Clichés you hate, things you do not want to promise, claims you cannot back up.

A reusable template, shown filled in for an illustrative case (a freelance designer chasing an overdue invoice). Swap each line for your own letter type, people, goal, facts, tone, format and things to avoid:

Write a payment reminder letter from me, a freelance designer who has worked with them for two years, to Dana Lee, finance manager at the client.
Goal: after reading, I want them to pay invoice 2026-114 by 30 November.
Facts (use only these, do not invent details):
- Invoice 2026-114, EUR 2,400, sent 1 October, due 31 October
- One earlier reminder sent by email on 5 November, no reply
Tone: polite, firm but not angry.
Length/format: under 150 words, plain email.
Avoid: threats of legal action, late-fee amounts not in my contract.
If any information is missing, ask me instead of making it up.

The last line matters more than it looks. It turns silent invention into a question you can answer.

Worked examples

The examples below are illustrative. Names, numbers, and companies are invented for the walkthrough.

1. Complaint letter (refund request)

Weak prompt: “Write a complaint letter about a broken blender.”

The result is generic: “I am writing to express my dissatisfaction with a recent purchase”, no order details, no clear request, and usually a vague threat to “take further action”.

Strong prompt:

Write a complaint email from me (Sam Rivera, customer) to the customer service team at an online kitchen store.
Goal: a full refund of $89.99 to my original payment method within 14 days. I do not want a replacement.
Facts (use only these):
- Order #48213, delivered 2 September
- Blender stopped working on 20 September after about 10 uses
- I contacted support by chat on 22 September; was told someone would reply in 48 hours; no reply
- I still have the blender and the box
Tone: firm and polite, not angry.
Length/format: under 180 words, plain email.
Avoid: legal threats, sarcasm.

What a good draft looks like (excerpt):

Subject: Refund request for order #48213

Hello,

I am asking for a full refund of $89.99 for order #48213, delivered on 2 September. The blender stopped working on 20 September after about ten uses.

I contacted your support team by chat on 22 September and was told I would hear back within 48 hours. I have not received a reply.

I would prefer a refund to my original payment method rather than a replacement. I still have the blender and its packaging and can return it if you send a return label. Please confirm the refund by 6 October.

Notice what makes it work: the request is in the first sentence, the facts are in order, and the deadline is specific.

2. Cover letter

Cover letters are where AI drafts fail most visibly, because recruiters read hundreds of them and the AI defaults (“I am excited to apply”, “proven track record”, “fast-paced environment”) are instantly recognisable.

Give it the raw material:

Write a cover letter for a Customer Success Manager role at a B2B software company.
About me: 4 years in account management at a payroll software company. Managed 60 mid-market accounts.
Two specific achievements (use exactly as written):
- Built an onboarding checklist that cut average time-to-first-payroll from 6 weeks to about 3
- Ran quarterly reviews for my top 15 accounts; none of them churned in two years
Why this company: they serve restaurants, and I worked in restaurants for 5 years before software.
Tone: direct, confident, no buzzwords.
Length: under 250 words, 3 short paragraphs.
Avoid: "passionate", "proven track record", "fast-paced", "I believe I would be a great fit".

Then edit: read it aloud, replace any sentence that could appear in anyone else’s letter, and check that every claim matches your CV.

3. Formal business letter

For a letter to a supplier, landlord, or authority, the format matters as much as the wording. Ask for it explicitly:

Write a formal business letter in block format: sender address, date, recipient name and address, subject line, salutation, body, closing, signature block.
From: Harbour Lane Studio (our company, illustrative), to: BrightClean Services (the supplier), about: giving 60 days' notice that we will not renew our cleaning contract ending 31 December, per clause 9.2.
Tone: neutral and professional. Thank them for the service. No reasons beyond "a change in our facilities plans".

For anything contractual, check the notice period and clause number against the actual contract. The model will happily repeat whatever you tell it, including the wrong clause.

4. Recommendation letter

The writer of a recommendation letter usually knows the person well and struggles with the format. Give the model specific stories, not adjectives:

Write a recommendation letter for Priya Shah, who reported to me for 3 years as a data analyst.
Stories to include:
- Rebuilt our monthly sales report so it runs in 10 minutes instead of 2 days
- Trained 4 new analysts; two now lead their own projects
- Flagged a pricing error before a client renewal that would have cost us the account
Tone: warm, specific, credible. Avoid superlatives like "best ever".

Specific stories are what make a reference letter believable. Adjectives without evidence read as a favour.

The edit checklist for every AI-written letter

Run through this before you send anything:

1. Facts. Every date, amount, name, and reference number matches your source. Nothing was added.
2. The ask. The action you want is stated clearly, once, near the start or the end.
3. Tone. Read it aloud as the recipient. Would you be annoyed, confused, or bored?
4. Generic lines. Delete any sentence that could appear in anyone’s letter. Our guide to the signs of AI writing lists the phrases readers spot first.
5. Length. Most letters are too long. Cut the first sentence if it only announces what the letter is about.
6. Promises. Make sure the letter does not commit you to anything you did not intend: a deadline, a discount, an admission.
7. Format. Correct salutation, sign-off, and contact details, and the right format for the channel (email vs printed letter).

Privacy: what not to paste

Letters often contain personal data: health details in a sick-leave letter, account numbers in a complaint, salaries in a reference. Before you paste, check your AI tool’s data policy and your employer’s rules. Replace sensitive details with a neutral stand-in in the prompt (for example, write “the account number” instead of the number itself), and add the real values yourself in the final version.

Letters at work: keep the voice consistent

One letter is a personal task. A team sending client letters, renewal notices, apology emails, and partner outreach every week has a different problem: every person and every prompt produces a slightly different voice. That is where a shared style guide and saved prompts pay off. Copyium’s brand voice feature stores your tone rules and banned phrases once, so every draft starts from the same voice. For persuasive letters and sales emails, our copywriting email examples and AI copywriting tips cover the next step.

Quick answers

Can AI write a letter for me? Yes, it can write a solid draft in seconds. It cannot know facts you did not give it, so you need to supply the details and check the result.

Is it acceptable to use AI for a cover letter? Many employers accept AI-assisted writing, but a letter full of generic AI phrasing hurts your chances. Use AI for structure and editing, and make sure the examples and motivation are genuinely yours.

What is the best prompt for AI letter writing? One that states the letter type, the goal, the sender and recipient, the exact facts, the tone, the length, and what to avoid, and tells the model to ask rather than invent missing information.