Practical. No hype.
The first time I asked Claude to write a referral letter, it came back polished, professional, and completely wrong. Not factually — the clinical content was fine. But it didn’t sound like me. It sounded like someone who had read a lot of referral letters and written a composite. That’s not what I needed.
The fix is not complicated, but it requires doing something most people skip: telling the AI how you write, not just what to write.
Why AI defaults to generic
Large language models are trained on enormous volumes of text and learn to produce outputs that average out across that training data. When you give no style guidance, you get the average. In writing, the average is bland — complete, grammatically correct, and recognisably nobody in particular.
A study published in May 2026 found that AI-assisted writing produced measurable shifts in voice: users submitting AI-assisted essays used significantly fewer first-person pronouns and fewer references to personal experience, resulting in more impersonal, formulaic output — regardless of whether that was what they intended (Axios, May 2026). The risk is not that AI writes badly. It’s that it writes well enough to replace your voice without you noticing.
The practical implication for surgeons: if you’re using AI to draft letters, summaries, emails, or any communication that goes out under your name, you need to explicitly protect your voice — otherwise the AI will supply its own.
The voice fingerprint method
The most reliable approach I’ve found is what I call a voice fingerprint: a short, explicit description of how you write that you give to Claude at the start of any drafting task. You can build this once and reuse it across your Claude Project (covered in detail in this setup guide).
To build a voice fingerprint, give Claude three or four pieces of your own writing — letters you’ve already sent, clinic letters, emails to colleagues — and ask it to describe your style. Then read that description, correct what’s wrong, and save it. You now have a paragraph that describes your voice that you can paste into any drafting request.
A useful starting prompt:
I’m going to paste three letters I’ve written. Read them carefully, then describe my writing style — sentence length, tone, how formal it is, what I tend to avoid, and any distinctive features. Be specific. I’ll use this description when asking you to draft things for me.
After Claude responds, test it: ask it to draft something in that described style, then compare it against your actual writing. Where it misses, correct the description.
Using Project instructions to make it permanent
The voice fingerprint only works if you actually use it. The easiest way to make that happen is to paste it into the system prompt of a Claude Project dedicated to your clinical writing. Once it’s in the project instructions, you don’t need to paste it into every conversation — it’s applied automatically.
The system prompt can be short. Something like:
You are helping me draft clinical correspondence and communications. My writing style: direct, short sentences, no hedging language, minimal jargon, informal but precise. I never start a paragraph with “It is important to note.” I tend to reference the patient’s specific circumstances rather than making general statements. Match this style unless I tell you otherwise.
Adjust that to fit your actual style. The point is that specificity works where generality doesn’t. “Formal and professional” is useless guidance — it means nothing beyond average. “Short sentences, no passive voice, clinical detail in the first line” is actionable.
What to do when it still misses
Even with a good voice fingerprint, Claude will occasionally produce something that doesn’t sound like you. When that happens, mark the specific lines that are wrong and explain why — “this sentence is too long,” “this sounds like a template,” “I would never use the word ‘pertaining.'” The model learns within the conversation and will adjust. Over time, your corrections refine the voice fingerprint itself.
The goal is not to automate your writing. It’s to make the first draft close enough that editing takes five minutes instead of twenty.
Next in this series: How to get AI to remember things — what persists between conversations, and how to make sure the things that matter actually stick.
Want to build this properly for your own writing? Logged-in members can book a session — 30 minutes (£75) to troubleshoot and set up your voice fingerprint together, or 60 minutes (£150) to build out a full clinical writing Project. We’ll work through your letters, your style, and leave you with a setup you’ll actually use.
References
- Axios. AI is changing the style and substance of human writing, study finds. May 2026. axios.com