What is Google-Extended?

Google-Extended is a control token that Google introduced in September 2023. You reference it in robots.txt the same way you would name any crawler, but it is not a crawler and you will not see it in your server logs. Googlebot fetches your pages as normal, then Google checks whether your robots.txt disallows Google-Extended. If it does, Google says it will not use that content to improve Gemini models or as grounding material for Gemini answers.

The token controls Gemini training and grounding only, and this is where most of the confusion sits. Blocking Google-Extended does not remove your pages from search results or change your rankings, and it does not keep you out of AI Overviews or AI Mode. Google treats those as Search features built on the ordinary index that Googlebot collects. According to Google, the controls that do affect them are standard search directives such as nosnippet, or blocking Googlebot itself, and both of those also cut your normal search visibility.

Before blocking the token, it is worth asking what you actually gain. Content that Gemini cannot learn from or ground against does not vanish from Gemini's answers. The model falls back on whatever it already holds in memory, and memory is where brand descriptions go wrong. In Discoverable's July 2026 study of 30 brands, AI misdescribed 27 of them (90 percent) when answering from memory, compared with 13 of 30 (43 percent) when it could use live search. Blocking training makes stale answers about your brand more likely without making the brand invisible.

Plenty of sites blocked Google-Extended in a blanket anti-AI clause and have since forgotten it is there. Discoverable's free AI crawler checker reads your robots.txt and reports which of 12 AI crawler tokens you block, Google-Extended among them. It also checks whether you publish an llms.txt file, and it takes a URL and no login. If you do want to opt out of Gemini training while staying in Search, Google-Extended is the correct tool for that specific job. Just do not expect it to change what appears in AI Overviews.