Definition
Content-Signal
Content-Signal is a declaration in robots.txt that states a site's preferences for search indexing, AI answer generation, and AI training.
The declaration uses the values search, ai-input, and ai-train. For example, Content-Signal: search=yes, ai-input=yes, ai-train=no states different preferences for those three uses.
A declaration does not itself block access to a page. A provider's published policy determines how it handles the signal. If you need an access restriction, review crawler rules and server or CDN controls separately.
Check the robots.txt file served to visitors, including any section managed by your CDN. The published declaration may differ from the file in your repository. Review it against the policy your team intends to publish.
Frequently asked questions
Does Content-Signal stop AI training?
The line itself does not enforce an access restriction. Check each provider's policy and use suitable server controls if access must be blocked.
Why is there a Content-Signal line I did not add?
Your CDN may manage part of robots.txt. Check its settings and the file actually served by your site.
What do the three values mean?
search refers to search indexing, ai-input to use in generated answers, and ai-train to model training. Each value can be yes or no.