What should the document contain?

Concrete instructions, paired examples showing a wrong version and a right one, and a list of words and claims you never use. Half a page of that beats twenty pages of adjectives, for a tool and for a new colleague alike.

Why did this only become a problem now?

It did not, it became visible. A voice held in a few people's judgement scaled as far as those people could read everything, and the volume of drafts these tools produce is usually where an organisation meets that limit for the first time.

Is it worth doing if we barely use these tools?

Yes, and that is what makes it easy to justify to anybody holding a budget. A documented voice speeds up new colleagues, settles recurring arguments and shortens review, and none of those benefits depends on a single word ever being produced by a machine.

Glossary

Brand voice

The documented way an organisation writes, which is what a tool has to be given before its output can match everything else you publish.

In plain terms

How your organisation writes, written down. Most places have never done this. They have two or three people who know it, and everything published passed through one of them, which worked until the volume of drafts stopped being something a person could read.

Why it matters

Because these tools did not create this problem, they revealed it. A voice held in a few people's judgement scaled exactly as far as those people could read, and the first month of AI-assisted drafting is usually where an organisation discovers that limit.

How it works

A tool can be given rules and cannot be given a feeling. Whatever is in somebody's judgement has to be turned into statements before it can be applied by anything other than that person, and doing so is the work.

The useful document is shorter and more specific than a style guide. Half a page of concrete instructions with examples does more than twenty pages of adjectives, because a machine and a new colleague both need to be told what to do rather than how to feel.

Examples carry more than descriptions. A pair showing something written the wrong way and then the right way settles questions that a paragraph about tone leaves open, and the pairs are also the fastest thing to assemble from work you have already published.

Prohibitions do a disproportionate amount of the work. The words you never use, the claims you do not make and the constructions you avoid are easy to state, easy to check and account for most of what makes copy sound wrong.

Writing it down surfaces disagreements that were previously invisible. Two people who both know the voice will differ on specific cases, and that difference was being resolved silently by whoever happened to review a piece, which is not a system.

The exercise is worth doing for its own sake. A documented voice speeds up new colleagues, settles arguments and reduces review time regardless of whether a single word is ever produced by a machine, which is what makes it easy to justify.

Two things called a brand voice

The most useful part of this exercise is not the document, it is the argument that produces it. Asking two people who both know the voice to write down the rule for a specific case reliably reveals that they were applying different rules and reconciling them by talking, which is invisible while the volume is low and impossible once it is not. Settling those disagreements is a day of work and it improves everything afterwards, including the writing nobody automates. The shortcut worth taking is to build the document from what already exists rather than from first principles: find six pieces you are proud of, six that felt wrong, and write down what distinguishes them. That produces concrete instructions and paired examples in an afternoon, which is the format a tool can use and, not coincidentally, the format a new colleague learns from fastest.

Seen in the wild

A tool producing competent copy that sounds like somebody else's company.
Writer
Half a page of instructions with paired examples, kept where drafts are written.
Notion AI
A generated deck matching the format and missing the register entirely.
Gamma

Common misconceptions

People assume

We already have one.

In fact

Most organisations have a feeling held by a few people and a document about values. What a tool needs is instructions and examples, and the absence of those is usually discovered in the first week rather than known in advance.

People assume

It is a tone-of-voice document.

In fact

Adjectives describing how the writing should feel cannot be applied by anything. Concrete instructions, paired examples and a list of what you never say can be, and they are also more useful to a new colleague.

Questions

What should the document contain?: Concrete instructions, paired examples showing a wrong version and a right one, and a list of words and claims you never use. Half a page of that beats twenty pages of adjectives, for a tool and for a new colleague alike.
Why did this only become a problem now?: It did not, it became visible. A voice held in a few people's judgement scaled as far as those people could read everything, and the volume of drafts these tools produce is usually where an organisation meets that limit for the first time.
Is it worth doing if we barely use these tools?: Yes, and that is what makes it easy to justify to anybody holding a budget. A documented voice speeds up new colleagues, settles recurring arguments and shortens review, and none of those benefits depends on a single word ever being produced by a machine.