How to make Claude write copy that doesn't sound like a robot

Research from X, Reddit, and Anthropic docs. 3 parallel agents. Synthesis below.

Strategy options — pick what you want

Recommendation: B + E first (cheapest, biggest leverage). Then A for CallSetter + ComiAI. Hold C until B+E aren't catching enough.

Agent 1 — X / Twitter research

Top techniques

1. Give it an identity, not a task. The single most cited fix on X. From @infooperative's Ogilvy Injection system prompt:

Role: You are an Ogilvy-level Direct Response Copywriter with 30 years
of experience in high-pressure sales. You despise fluff, jargon, and
corporate speak.

2. The 3-file context system (Anthropic engineers endorse this). From @FerTech quoting Anthropic's "context engineering" post (Sep 2025): "Finding the smallest possible set of high-signal tokens that maximize the likelihood of some desired outcome." Three files to attach to every Claude session:

• ABOUT-ME.md — who you are, your brand, your customer
• VOICE.md — how you write, what you sound like
• ANTI-STYLE.md — what you'd never say, patterns to kill

3. Negative-example file. @FerTech confirms Anthropic validated this as a "legitimate negative-example technique." Contains: 5-10 real examples of your worst AI-sounding outputs + banned phrases + "I would never say X because..."

4. Banned-phrase hard constraint in system prompt. From @infooperative + @godofprompt:

Banned words: leverage, synergy, unlock, elevate, dive in,
game-changer, seamlessly, revolutionize, cutting-edge, navigate,
empower, journey, transform. Use them and the copy is dead.

Put this in the SYSTEM prompt, not the user message. It sticks harder.

5. Reading-level + sentence-length lock. @infooperative: "Grade 4 reading level. Short sentences. Punchy. Fragmented. Like this." @f3dericobartoli on sentence-length fingerprinting: measure target's average sentence length and short/long ratio, replicate exactly.

6. Micro-persona voice-cloning for cold email. @peterczepiga's chained prompt: "First generate 25+ micro-personas for this ICP. Then for each, write 4 first-person pain points. Use those verbatim as copy hooks." First-person pain language IS human.

7. "Write like you talk" + out-loud test. @godofprompt's VSL prompt: "Write like you talk. Read every sentence out loud in your head. If it sounds like a textbook or a press release, rewrite it." Add this literally to system prompt.

8. The Copychiefer QA pass. @f3dericobartoli runs a dedicated Claude Project whose only job is de-slopping AI-generated copy. Two-pass beats one-pass every time.

9. Required human patterns list (flip side of banned). @godofprompt:

REQUIRED: Use contractions (you'll not you will). Let sentences be
imperfect. Fragments are fine. Starting with 'And' or 'But' is fine.
Vary openings: nouns, verbs, prepositions, numbers, questions.
Never fall into a repeating rhythm pattern.

10. Specificity mandate. AI defaults to abstract. Force it concrete:

Concrete over abstract always. '45 minutes' not 'a short time.'
'$4,200' not 'significant revenue.' 'HVAC contractors in Phoenix'
not 'local businesses.'

11. PAS + identity injection. @infooperative's most-cited structure: Hook = counter-intuitive statement or specific number. Agitation = twist the knife. Solution = mechanism, not product. Tone = arrogant but competent.

12. Grok for hooks, Claude for body. @habibi_davidd nearly doubled hook rate by handing hooks to Grok (different training distribution) and body copy to Claude.

Direct quotes from X

"It sounds robotic because you gave it no persona. No constraints. No emotional stakes. Bad prompts = robotic slop. Great prompts = cash in the bank. I stopped giving LLMs tasks. I started giving them identities." — @infooperative

"This one is trained on copy chiefing direct response + de-slopping AI-generated copy. It transforms basic plain AI copy into human-sounding copy with crazy accuracy." — @f3dericobartoli

"Use prompt-chaining. First identify 25+ micro personas. Then for each, generate 4 first-person pain points. Many copy lines, used verbatim, are better than most ad copy." — @peterczepiga

Agent 2 — Reddit research

Top techniques

1. Anti-AI Editor Prompt (Ruben Hassid, widely reshared on r/ClaudeAI). Paste before any copy rewrite:

Act as my Anti-AI-Voice Editor. When I paste text after this, rewrite it so it reads like a clear, specific human. Not like ChatGPT, Claude, or a generic AI thought leader. Preserve content, POV, length, and structure. Hard-ban 80+ words like delve, harness, paradigm, innovative, disruptive. Replace the "In a world where" opener, the "Most people vs. The few who" contrast, and the "Stop doing X. Start doing Y" formula.

2. Human Writer Role Block.

You're a human writer who creates authentic, conversational content. Use contractions freely. Vary rhythm: punchy short sentences followed by longer ones that breathe. Start sentences with "And" or "But." Use fragments for emphasis. Include specific concrete details rather than abstract concepts.

3. Master Rewrite Prompt (r/PromptEngineering).

You are my editor. Rewrite the text I paste so it reads like a sharp human wrote it. Maintain meaning. Remove fluff. Use active voice. Vary sentence length. Ban em dashes. Eliminate: delve, tapestry, game-changing, unlock, robust. Do not fabricate facts.

4. Voice-Clone Interview (100 questions). Paste to Claude, answer one at a time, save output as a .md file:

You are my Taste Interviewer. Ask ONE question at a time across these categories: Beliefs/Contrarian Takes (15), Writing Mechanics (20), Aesthetic Crimes (15), Voice/Personality (15), Structural Preferences (15), Hard Nos (10), Red Flags (10). Push back on vague answers. If my answer could describe any writer, flag it. Don't accept "I don't know" easily.

5. Claude Projects Brand Voice System. Claude Projects system instructions have no character limit. Paste your entire brand voice guide there. Add 3-5 example sentences inline. Claude references it automatically every message. Key instruction:

Describe what the brand never uses. We never use corporate hedging phrases. We never write "leverage" or "synergy" or "solutions." We never open with grand statements about the world.

6. Cold Email Persona (direct response grade).

You are a senior cold email strategist who has spent 15 years at the intersection of direct response copywriting, behavioral psychology, and B2B outreach. Write ONE cold outreach email. Steps: (1) Recipient mental model analysis, (2) Connection mapping, (3) Status calibration, (4) Emotional trigger selection, (5) Deletion risk audit. Max 150 words body. Max 7-word subject line.

Before / After

Robotic "In today's rapidly evolving digital landscape, it's crucial to leverage cutting-edge solutions that foster growth and unlock transformative potential for your business."

Human "Most software promises to fix your operations. Most doesn't. Here's what actually worked for 400 contractors we surveyed."

Robotic cold open "I hope this email finds you well. I wanted to reach out because I came across your profile and thought there might be synergy between our companies."

Human (Eric framework) "Noticed [CompanyName] runs emergency HVAC calls 24/7. When that 2 AM call comes in Saturday, is it hitting your dispatch board or a voicemail?"

Claude-specific tips from Reddit

• Claude Projects system prompt has NO character limit. Paste your full voice guide there.
• Claude Styles (Settings): create named presets per content type. Switch with one click.
• Upload voice .md to Project Knowledge. Claude references without being asked.
• XML tags help structure long system prompts: <voice>, <banned_words>, <examples>, <constraints>.
• Claude defaults to "polished, professional, centrist prose." If your brand is sharp or irreverent, you must explicitly say so.
• Claude Opus 4.7 is more direct with less validation phrasing. If your brand needs warmth, you have to specify it now.

Agent 3 — Anthropic docs + Google

Anthropic's official position (verbatim)

Examples are one of the most reliable ways to steer Claude's output format, tone, and structure. A few well-crafted examples (known as few-shot or multishot prompting) can dramatically improve accuracy and consistency. Include 3-5 examples for best results. Wrap examples in <example> tags so Claude can distinguish them from instructions. platform.claude.com docs

Setting a role in the system prompt focuses Claude's behavior and tone for your use case. Even a single sentence makes a difference.

Providing context or motivation behind your instructions, such as explaining why such behavior is important, can help Claude better understand your goals.

Anthropic ships their own anti-slop snippet for frontend code that applies equally to copy: "NEVER use generic AI-generated aesthetics like overused font families, cliched color schemes, predictable layouts. The same logic applies: ban the defaults explicitly."

The 4 prompt structures that work

A. Persona + voice samples (most reliable).

<system>
You are [NAME], a [ROLE] who writes cold email and sales copy.
Voice rules:
- Short declarative sentences. Fragments when a human would use them.
- Concrete numbers always: "$5k", "2 AM". Never "a lot."
- One specific reference to the prospect per email.
- Low-friction CTA ending in "?"
- No corporate "we provide" / "we offer" language.

<examples>
  <example>
    Subject: missed call
    Body: When a homeowner calls at 2 AM about a burst pipe, is your
    answering service booking the $4k emergency job or taking a message?
    We built {{companyName}} a voice agent that handles exactly that.
    Want me to send it over?
  </example>
</examples>
</system>

B. XML-tagged constraint list.

<voice_rules>
NEVER write:
- "I hope this finds you well"
- "I wanted to reach out"
- "leverage" / "utilize" / "delve" / "tapestry" / "holistic"
- em dashes — or en dashes –
- "It's important to note"
- Sentences starting with "This is"
- "Not only X but Y" constructions

ALWAYS write:
- Sentences under 15 words unless breaking that rule makes a point
- At least one specific number per paragraph
- CTA as a question, never a command
</voice_rules>

C. Voice DNA interview (one-time setup, reuse forever). Run once on Claude, save as a .md file:

Ask me 40 questions one at a time about my writing voice. Cover:
- What I write and who I write for
- Phrases I use naturally
- Words I hate
- My formatting instincts
- Writers I admire
- Feedback I keep getting

Rules: push back on vague answers, ask for real samples, don't
validate my answers, one question at a time. When done, output a
structured Voice DNA file with: Core Identity, Always/Never quick
reference card, 3 real writing samples I gave you.

D. Iterative refinement (post-draft pass). After Claude writes copy, run a second pass:

You are a copy editor trained on [WRITER]'s voice.

Review the draft below and:
1. Flag every sentence that sounds AI-written
2. Identify all -ly adverbs and replace them
3. Find every sentence over 20 words and break it
4. Find all abstract nouns and replace with concrete equivalents
5. Score: Directness (1-10), Rhythm (1-10), Trust (1-10), Authenticity (1-10)
6. Rewrite the flagged sections.

Master banned-word list (from willfrancis.com + github.com/hardikpandya/stop-slop)

Top 5 articles

1. How to Stop Claude Writing Like an AI — Will Francis. Most comprehensive single-page checklist.
2. The Claude Skills That Finally Made AI Write Like Me — three-skill structure as persistent files.
3. How to Make Claude Write Like You — Artificial Corner. 40-question voice cloning protocol.
4. Steal Eric Nowoslawski's Cold Email Engine — concrete signals beat generic personalization.
5. github.com/hardikpandya/stop-slop — open-source Claude skill targeting 20+ AI writing patterns. 5-dimension scoring system.

Key insight from all sources