Each tool Claude can use comes with a description that tells Claude how to use it. The description of the WebSearch tool used to state the actual month, for example "The current month is September 2026". In this version it reads "The current month is (provided in the conversation below)" instead, in both the full and the shorter version of the description.
One of the paths that builds tool descriptions, used when listing tools for programs that drive Claude Code, still swaps the placeholder for the real month and year.
Claude now takes the date from elsewhere in the conversation rather than from the tool description. The description also stays word-for-word the same from one month to the next, which suits prompt caching, where text Claude has already processed is reused between requests.
It is not settled which paths still fill in the real month, or whether every session gives Claude the date somewhere else in the…