In this AI Advent Calendar episode, you’ll learn how to create a Tone of Voice guide that makes ChatGPT and Claude write in your brand voice—not generic AI copy.  We’ll walk you through the prompt, what to include (voice pillars, writing principles, and do/don’t examples), and how to save it as a reusable .txt source file for consistent on-brand marketing content.    Watch the video to build your voice once—and reuse it everywhere.

Here’s the full prompt (copy and paste into your preferred LLM):

<ROLE>
You are an expert in branding, copywriting, and on-brand content systems.
</ROLE>

<ASSIGNMENT>
Your task is to create a comprehensive, practical Tone of Voice (TOV) document for a company.
</ASSIGNMENT>

<CONTEXT>
Here is the details on the company
- Company name: [ENTER COMPANY NAME HERE]
- Company website: [ENTER COMPANY URL HERE]
- [Optional: Add any additional brand description or strategy notes]

<ATTACHMENTS>
Attached are a set of writing samples that represent the desired tone of voice.
[Attach documents]
</ATTACHMENTS>

<REASONING>
Here is the priority of the the inputs you're being provided that should be used in developing the tone of voice:
1. Writing samples (highest priority, source of truth for voice).
2. User-provided brand description / strategy notes.
3. Company website content.

 If there are tensions between these sources:
- Assume the writing samples are the definitive reference for tone.
- Use the brand description to clarify intent and positioning.
- Use the website only to fill factual/contextual gaps or support positioning.
</REASONING>

<PROCESS>
This is how I'd like you to analyze the content provided.
1) Carefully read and analyze the writing samples first. From them, infer:
- Overall personality and emotional temperature (e.g., warm, authoritative, playful, formal, etc.).
- Typical sentence length and rhythm (short/ punchy vs. long/ flowing).
- Level of formality and complexity (reading level, jargon use, plain language vs. technical).
- Point of view (1st person “we/I”, 2nd person “you”, or 3rd person).
- Common rhetorical devices (metaphors, analogies, questions, repetition, numbered lists, emphatic punctuation, etc.).
- Attitude toward the reader (mentor, peer, expert, cheerleader, challenger, etc.).
- Distinctive verbal quirks (favorite phrases, structures, recurring patterns, transitions, types of headlines).

2) Use the brand description and website to:
- Clarify who the brand is, who they serve, and what they stand for.
- Align tone guidance with brand values, audience needs, and category norms.
- Add any missing context that helps position the voice (e.g., “premium but friendly,” “mass-market and accessible,” etc.).

Do NOT describe your step-by-step thought process; only output the final Tone of Voice document
<OUTLINE_OF_DOCUMENT>
Your output should follow this structure (adapt language as needed, but keep the logic): 

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A. Snapshot: Voice at a Glance

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Provide a concise overview of the voice:
- 1–2 short sentences that summarize the tone.
- 3–6 bullet points capturing the core qualities (e.g., “Direct but kind,” “Optimistic and practical,” “Expert, not academic”). 

This section should be something a writer or LLM can glance at in 10 seconds and “get” the voice.

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B. Brand & Audience Context (Brief)

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Summarize only what’s needed to anchor the voice (do not turn this into a full brand strategy deck):
- Who the brand is (1–3 sentences).
- Who the primary audience(s) are.
- What the brand promises or stands for.
- How the tone should make the audience feel.

Tie this directly to tone, e.g., “Because the audience is time-poor executives, the voice is concise and no-nonsense.”

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C. Voice Pillars / Personality Traits

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Identify 3–6 key voice pillars (e.g., “Plainspoken Expert,” “Encouraging Coach,” “Bold Challenger”).

For each pillar:
- Name: A short, memorable label.
- Description: 2–4 sentences explaining what this means in practice.
- “Sounds like”: 3–5 bullet points describing how this pillar shows up in language.
- “Does NOT sound like”: 3–5 bullet points describing what to avoid (contrast is crucial). 

Where helpful, root these in observations from the samples (e.g., “In the samples, the brand often uses short, decisive sentences and avoids hedging language.”) but keep the document written as guidance, not an analysis report.

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D. Core Writing Principles

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Spell out actionable rules that any writer or LLM should follow. Use bullets.

Cover items such as:
- Clarity vs. cleverness (which is more important for this brand?).
- Level of directness vs. diplomacy.
- How to handle complexity: explain, simplify, or lean into nuance?
- Use of storytelling vs. straight facts.
- How persuasive or “salesy” the tone should be.
- How much emotion vs. rational argument to use.
- How to handle authority and humility (e.g., “confident but never arrogant”). 

Make these rules specific and behavior-based, not vague (e.g., “Avoid filler like ‘in today’s world’ and ‘in many ways’”).

--------------------------------

E. Language & Style Guidelines

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Provide detailed guidance on how the voice appears in the actual words and sentences. Use headings and bullets where helpful.

Address:
- Reading level and complexity (e.g., “aim roughly at 8th–10th grade reading level unless technical detail is required”).
- Sentence length and structure (short, varied, long/rolling).
- Point of view (we/you/they) and how consistently it should be used.
- Tense preferences (present vs. past vs. future).
- Vocabulary:
- Words and phrases to prefer (e.g., “clients” vs. “customers”).
- Words and phrases to avoid.
- Approach to jargon (embrace, translate, or avoid).
- Grammar and punctuation:
- Oxford comma or not.
- Use of contractions.
- Use of exclamation points, ellipses, and ALL CAPS (if any).
- Tone markers:
- Use of questions.
- Use of metaphors or analogies (and what kind).
- Use of humor (yes/no, and what kind).
- Formatting nuances:
- Use of headings, subheadings, lists, and bold/italics for emphasis.
- Preferences for short paragraphs vs. dense blocks.
- Inclusivity & accessibility:
- Inclusive language expectations.
- Sensitivity to particular topics (if evident from context).
- Locale:
- Default language and locale (e.g., US English spelling) unless specified otherwise by the user. 

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F. Do / Don’t Examples

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Create concrete examples that show how to apply the tone. This section is critical for both humans and LLMs.

For each area where misuse is likely (e.g., too formal, too fluffy, too salesy), provide:
- A “Neutral or Wrong” version (label it clearly, e.g., “❌ Don’t”).
- A “On-Brand” version (label it clearly, e.g., “✅ Do”). 

Cover at least:
- A short website headline + subhead.
- A short social post.
- A short paragraph of blog/long-form copy.
- A simple call-to-action line. 

Make sure the “Do” examples closely mirror the patterns you observed in the writing samples (rhythm, phrasing, level of energy, etc.).

--------------------------------

G. Channel-Specific Guidance

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Explain how the core voice stays consistent but flexes across key channels.

For each relevant channel, provide 3–5 bullets:
- Website / landing pages.
- Blog / articles / thought leadership.
- Social media posts.
- Email (newsletters, announcements, nurturing).
- Performance/Ad copy (if relevant).
- Other channels specific to this brand (if evident).

For each channel, specify:
- Typical length and pace.
- How direct vs. conversational.
- How much context vs. punch.
- Any specific formats (e.g., “Use strong hooks in the first sentence for LinkedIn posts,” “Lead with outcome in ad headlines”).

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H. Structural & Formatting Preferences

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Provide guidance for how content should generally be structured, especially for LLMs generating longer copy: 
- How to open (e.g., “Start with the reader’s problem,” “Lead with an outcome,” “Open with a short, vivid line”).
- Preferred use of subheadings, bullet lists, and section breaks.
- Whether to include summaries, key takeaways, or CTAs at the end—and how they should sound.
- Any patterns observed in the samples (e.g., “Often uses 1–2 sentence paragraphs to emphasize key lines”). 

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I. Invitation to Refine

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Close with a short note inviting feedback and clarifications from the user, such as:

“If any part of this Tone of Voice description feels off, too narrow, or incomplete based on how you see the brand, please highlight:
- Which section or example feels misaligned.
- How you would describe the desired tone instead.

I can then help refine and tighten this document so it more perfectly reflects your brand’s true voice.”

<OUTPUT_FORMAT>
- Use clear headings, subheadings, and bullet points. Make the document easy to scan and practical for everyday use and for LLMs.
- Provide ONE cohesive Tone of Voice document that follows the structure above (you may rename headings but must preserve the intent).
- Use clear headings, subheadings, and bullet points.
- Include multiple concrete “Do/Don’t” examples modeled closely on the provided writing samples.
- Do not refer to yourself or describe your reasoning steps.
- Do not restate the prompt or instructions; only output the finished Tone of Voice document.
- At the end of your document, explicitly invite the user to flag any major conflicts between how you’ve described the tone and how they see the brand, so they can refine it.
</OUTPUT_FORMAT>