Google updated favicon docs after an AI prompt test, Mueller says

Google rewrote one bullet in its favicon documentation this week. The team did it after an internal AI prompt test, John Mueller from Google said on LinkedIn.

The old bullet said Googlebot and Googlebot-Image must be able to crawl the favicon file and the home page. The new bullet adds a sentence. Googlebot must also follow any redirects from the home page to the page where the favicon is specified. The bullet also now says these URLs must not be blocked by robots.txt or other means. The change is on the Google Search Central docs page for favicons.

Barry Schwartz at Search Engine Roundtable reported the change on 27 October. He called it a clarification. He then added an update: John Mueller had explained why Google made the edit.

What Mueller said

Mueller's words, as quoted by Search Engine Roundtable:

"Fun fact - we did this because we saw how AI systems didn't understand exactly how to investigate this. Probably this also applies to non-AI's :-). We tried the change as a prompt, and saw that it worked much better."

He gave the test prompt as an example: "record the guidelines https://xyz and investigate why the favicon on my website is https://abc not showing up in Google search". He said the new wording let the AI assistant work the task better. He added that this is now possible without a separate instruction file.

Why this matters

Mueller's post treats the Google docs as something that will be read by machines. The team wrote one version. They found it did not work as a prompt. They rewrote it. They published the rewrite as the public doc. A publisher that wants an AI reader to pass its own instructions to a user can take the same step. Rewrite the paragraph as a prompt. Try it on the model your audience uses. Keep the version that works.

Mueller gave one example, one page, and one quote on his own LinkedIn account. He did not say how many other Google docs have been edited this way. He did not say whether the AI prompt test is now part of the Google docs team's regular review. He also did not say which AI assistant was used.

What is still in the old wording

The new bullet keeps the two older rules. Googlebot-Image must be able to crawl the favicon file. The home page must not be blocked. What is added is the redirect chain from the home page to the favicon page.

The underlying rule is the same. If any step in the chain is blocked, the favicon does not show. The edit only changes the wording. The behaviour of Googlebot is unchanged.

Source

Google favicon documentation. Barry Schwartz at Search Engine Roundtable.