Brand voice guidelines
Every template you can find for this is a blank container. A document with headings and nothing under them, a spreadsheet behind an email gate, a workbook you copy to your own drive. The blank is the easy half, and it is the half that does not work: a two-year-old forum thread asking what to actually put in one still ranks, which is the evidence.
So this page publishes the shape itself, field by field, with types and defaults. The schema is released under CC0, so you can take it and build your own thing with it without asking.
It is the document half of brand voice for AI, which covers the six files the rules end up in. If you would rather have this filled in than described, eleven questions produce a completed one.
What is in a tone of voice document that a model can act on?
A useful document splits into two halves that get confused constantly. One half is orientation: what the organisation does, who it serves, what it wants to be to them. That half is written for people and it belongs in the document your team reads.
The other half is instruction: settings and prohibitions that decide individual sentences. That half is what a model can act on, and in most published guides it is a page or two out of fifty.
The test for which half a line belongs to is whether a checker could decide, without discussion, whether a given sentence breaks it.
The fields, with types and defaults
| Field | Type | Default |
|---|---|---|
| brand_name | String, the named subject of every file | Required |
| brand_what | One sentence, 140 characters | Required |
| audience_primary | One of six reader types | Required |
| tone_formality | Forced choice, ships as a worked example | Required |
| tone_humour | Forced choice, ships as a worked example | Required |
| tone_irreverence | Forced choice, ships as a worked example | Required |
| tone_energy | Forced choice, ships as a worked example | Required |
| traits_never | List of prohibitions | Required |
| mech_person | We, I, by name, or mostly you | Required |
| mech_contractions | Always, never, or depends on surface | Required |
| locale_variant | One of six English variants | Required |
| mech_exclamations | Permitted, rationed, or forbidden | Rationed |
| mech_serial_comma | Boolean | Follows the locale |
| mech_heading_case | Sentence, title, or lower | Sentence |
| mech_em_dash | Permitted or forbidden | Permitted |
| lex_substitutions | Pairs: say this, not that | Empty |
| lex_mandated | Terms that must appear verbatim | Empty |
The eleven required fields are the ones asked before anything else, and they are enough on their own to produce a working file. Everything below them is optional and refines it. The eleven questions page gives the reasoning behind each one.
Which fields are rules, and which are decoration?
The mechanical fields are rules. Person, contractions, locale, punctuation and vocabulary each decide something in every sentence, and two people applying them independently will agree.
Everything expressed as an adjective is decoration in this specific sense: it cannot be checked, so it cannot be enforced, so a model can appear to honour it while doing whatever it was going to do anyway. That does not make it worthless to a human reader. It makes it inert as an instruction.
Why do adjectives not survive the trip into a model?
Because an adjective is a compression of decisions somebody already made, and the model has to decompress it with no access to what was compressed. Warm might mean contractions and second person to you and emoji to the model.
The fix is not to avoid the word. It is to write down the behaviour that made you choose it. Confident usually decompresses to no hedging words. Warm often decompresses to contractions, second person, and short sentences. Write the decompression and the adjective becomes unnecessary.
This is also why the four tone questions here are pairs of written paragraphs rather than sliders: the paragraph you choose ships in your file as a worked example, and an example needs no decompressing.
How long should it be?
Shorter than you think, and the number is fifteen binding rules with thirty as an absolute ceiling. That is not a limitation of this tool; it is the design.
Compliance with a set of constraints degrades as the constraints stack, and vendors say so in their own documentation. Anthropic states that longer instruction files consume more context and reduce adherence, and that if a rule keeps being ignored the file is probably too long. Cursor's anti-pattern list names copying entire style guides and tells you to use a linter instead.
Every documented length limit is collected here, including which of the widely quoted figures turn out not to exist.
Which parts a human reads and which parts only a machine reads
Both documents should exist and they should not be the same file. The human document carries positioning, audience, rationale and examples with commentary. The machine document carries the settings and prohibitions, in the format each tool reads, with nothing else in it.
Keeping them separate is what stops the machine file growing until it stops working. The manifest shows both, and every format the rules get rendered into.
What we left out, and why
- Brand archetypes. A diagnostic of perceived personality, not a source of writing rules.
- A tone spectrum with sliders. The most requested visual in the category, and the format with the worst response quality for this audience.
- A voice score. There is no defensible one: within a single author's register, paragraph-level readability varies by several grades, so any per-paragraph verdict is noise larger than the effect it claims to measure. The limits page explains that refusal and the others.
- Anything that would push you past the fifteenth rule. A field whose only effect is to make the file longer makes the file worse.
Where these come from
Every claim above is quoted from one of these, and each was read on the date beside it. If one of them has changed since, the page is wrong and we would like to know.
- Anthropic: instruction length and adherence checked 2026-08-16
- Cursor: rules, and the copy-a-style-guide anti-pattern checked 2026-08-16
- Mailchimp content style guide checked 2026-08-16
- GOV.UK style guide checked 2026-08-16
The schema on this page is what the tone of voice generator fills in, and it hands you the completed document plus every machine-readable rendering of it.