What
When Claude tries to start a comment thread on a page that keeps its own comment threads (for example a connected document), the comment tool now recognizes this case and refuses, with a message explaining that the page manages comments itself and that no comment has been sent to Claude yet there. Claude is told to use that page's own connector tools instead.
Why
This stops Claude from trying to add comments through the wrong mechanism on pages that have their own dedicated comment system, and points it toward the correct tool for that page instead.