Thomas Ptacek's rule, as quoted by Willison: "You may not use a single word an LLMA large language model — the neural network behind tools like Claude and ChatGPT, trained on huge amounts of text to predict what comes next.Full definition → suggests to you" — he treats any LLM-suggested turn of phrase as off-limits, calling the discipline a form of "intellectual personal protective equipment."
Willison describes his own narrower practice: he won't let an LLM draft content for his blog, but does use one for fact-checking, spelling and grammar, and as an occasional thesaurus via a dedicated proofreading prompt he has published.
Ptacek published a screenshot of his personal LLM copyediting tool along with a starter prompt so readers can build a similar tool themselves.
Terms in this piece · Glossary
LLM — A large language model — the neural network behind tools like Claude and ChatGPT, trained on huge amounts of text to predict what comes next.
Why it matters
A concrete, actionable discipline for keeping your own voice in documentation and blog posts while still using LLMs for proofreading and fact-checking.