Nearly every owner says the same thing when the subject of help with writing comes up: it has to sound like me. Or, in a firm, it has to sound like us.
Fair. And almost nobody can say what that means, which is a problem before any tool is involved, because it also means an assistant cannot draft for you, a colleague cannot answer on your behalf, a new hire cannot write the follow-up email, and your own website probably does not sound like you either.
This is how to write the document that fixes that. It is useful whether or not anything automated ever touches your words. It is essential if something does.
Do not start with adjectives
The standard brand exercise produces three words: warm, direct, professional. That document is worthless, because every business on earth picks roughly those three and none of them write remotely alike.
Adjectives describe the result. They do not tell anyone how to produce it.
Start with evidence instead.
Collect twenty things you actually wrote
Real ones. Emails to clients, a good message you sent a colleague, something you posted that felt right, the explanation you gave when somebody asked what you do at a party and you answered well. If other people in the business write to clients, include the pieces of theirs you would happily have signed.
Include a couple of things written when slightly annoyed, and one where difficult news had to be delivered. Voice under pressure is more distinctive than voice at ease, and it is the register a stand-in gets most wrong.
Then read them together in one sitting. Patterns you cannot see in a single message are obvious across twenty.
What to actually write down
Sentence shape. Do you run long or short? Most people alternate and have a characteristic rhythm. Note whether you tend to state the point first and then explain, or build to it.
Your actual vocabulary. The specific words you reach for repeatedly. Not the ones you think you should use. If you always say "the work" rather than "the service", write that down. This section is the most load-bearing part of the document and it should be a real list.
Your banned list. Sharper and easier to write. The words that would make a client think somebody else had written it. Mine includes leverage, scale as a verb, journey, unlock, and anything that sounds like a press release. Yours will differ, and the list is more diagnostic of your voice than the positive list is.
What you call people. Clients, customers, patients, members, the people we work with. Owners are often quite particular about this and almost never write it down, which means everyone else guesses wrong.
How you open and close. Do you greet? Do you sign off, and how? Do you ever use a person's name mid-message? These are small, consistent, and instantly noticeable when wrong.
How you handle the hard moments. Delivering bad news, declining something, disagreeing with a client, and following up when somebody has gone quiet. Write one real example of each, with a note on what you were doing and why. This section is what separates a usable document from a decorative one.
Your position on things. Not style at all, but it belongs here. The two or three views you hold that shape how you talk about your work. Voice is partly what you consistently refuse to say.
The tests that keep it honest
The subtraction test. Take one of your own messages and remove your name. Would a client still know it was you? If not, the document has not captured anything yet, or your writing is more generic than you think, which is worth finding out. It is also, roughly, the question behind whether people can tell your writing is AI.
The stranger test. Give the document and a real situation to somebody who knows you, and ask them to draft. Where they get it wrong tells you what the document is missing. This is the only reliable way to find the gaps, and it takes twenty minutes.
The wrong-mouth test. Write three sentences deliberately in the voice you are not. Corporate, guru, salesy. Naming the near-misses defines the boundary better than describing the target does.
Keeping it alive
Two pages, not ten. Anything longer will not be read by a person and is not more useful to a machine.
Add to it when you catch yourself writing something particularly you, and when somebody drafts on your behalf and gets it wrong. Those two events are the only maintenance it needs.
And it should be yours. If you ever work with anyone on systems that produce writing in your name, this document is the input, and you should keep the original rather than have it live inside somebody's tool. It is one of the few genuinely portable assets in a business, and it earns its keep most in the Engage stage, where an interested person's first reply from you decides whether they stay interested.
Questions owners ask
How long should a tone of voice document be?
Two pages. The value is in the specific vocabulary lists and the worked examples of hard moments, not in the description. A ten-page document describing your voice in the abstract will help nobody, including you.
Is this only useful if I plan to use AI?
No, and I would write one even if you never do. It makes your website better, it lets an assistant or a team member answer routine messages without sounding like a different business, and the act of writing it usually clarifies what you actually believe about your work. If you do use AI for any of it, whether to say so is its own question, which I took on in should you tell clients you use AI.
What if my voice is different with different clients?
Then write the core plus the variations, and be specific about what changes. Most owners find the underlying structure is constant and the register shifts, and naming exactly what shifts is more useful than pretending it does not.
Can I just point at examples instead of writing rules?
Examples alone leave the reader to infer the rule, and they will infer the wrong one. Examples plus a short note on what you were doing in each is the format that works, for a person and for anything else.