Simon Willison September 18, 2026 2 min signal 2026-09-18

How to write with an LLM

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17th September 2026 - Link Blog

How To Write With An LLM. Thomas Ptacek on using LLMs as copyeditors, not as writing assistants:

Rule Number One: You may not use a single word an LLM suggests to you.

[...] I think that as a form of intellectual personal protective equipment you should adopt the rule that any specific turn of phrase an LLM suggests is off limits. Be strict about the rule!

I won't let LLMs write content for my blog, but I use them for fact-checking, spelling and grammar and as an occasional thesaurus (see my proofreading prompt).

The rule to never use a turn of phrase suggested by an LLM feels good to me. The text has that weird smell to it, and it's also a good principle to help stay disciplined.

Later in this piece Thomas shows a screenshot of his personal LLM copyediting tool (see also this Twitter thread), and provides a prompt to help kickstart building your own.

Posted 17th September 2026 at 11:37 pm

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