How to Build an AI Style Guide

Katie Parrott traces style guides from Horace Hart’s 1893 rules for Oxford compositors through the AP Stylebook to the current need for AI style guides. Each new production technology — printing press, telegraph, screens — required new style rules. Language models open a new gap: they generate writing but default to generic, interchangeable prose.

The distinctive markers of a writer’s style are subconscious — word choice, sentence rhythms, patterns. Research shows humans are roughly twice as linguistically varied as machines, sentence to sentence. The only way to close that gap is to surface hidden patterns, name them, and write them as instructions.

Parrott describes her own process: feeding essays to ChatGPT, pushing back on its observations, then uploading the refined guide to a Claude Project. The piece offers a step-by-step framework for building an AI style guide from scratch, drawing on systems built at Every and for Spiral, their AI writing tool.

RDCO mapping: Directly applicable to our voice-match skill and CopyThat system. The method of using AI to interview you about your own patterns mirrors how we built the founder voice profile. Strong reference for any content about maintaining authorial identity in an AI-assisted workflow.