ChatGPT search now uses the site:operator at scale
Simon Willison's link post discusses a notable change in ChatGPT search behavior, tracked by Promptwatch, a tool in the emerging GEO (Generative Engine Optimization) space. Promptwatch uses automation to monitor responses across chat products like ChatGPT, Claude, and Gemini, publishing aggregate reports. Their data shows that the percentage of ChatGPT Search queries containing the site: operator hovered between 0.3% and 0.5% for weeks, dipped to 0.15% from August 3 to 5 (consistent with a staged rollout or pre-launch experiment), then jumped to 16-17% on August 8. This aligns with OpenAI's August 6th announcement about updating GPT-5.6 Sol in Chat for Plus and Pro users to be more reliable with facts and provide more focused answers. Willison notes that OpenAI obscures system prompts, but he believes the search tool now has a shape like search(query, recency, domains) rather than encouraging a site: operator directly. In a follow-up on August 18th, Promptwatch reported that ChatGPT appeared to have greatly reduced the likelihood of Reddit being used in those searches. Willison's attempts to confirm system prompt changes have been unsuccessful, as the most thorough leaked system prompt collection he knows of doesn't yet show relevant changes.
Developers may need to adjust SEO strategies as ChatGPT search increasingly uses the site: operator, affecting site visibility.