You'll notice
Reading a large PDF whose page count can't be determined now fails with a clear error
What
When Claude tries to read a PDF file and the tool can't determine how many pages it has (because the underlying pdfinfo check fails) and the file is large enough to cross a size threshold, it now throws a dedicated page_count_unknown error instead of just proceeding. The error tells the model to use the pages parameter to read the file in parts.
Why
This avoids Claude silently attempting to process a large PDF it can't properly size up, and instead points it toward a working approach of reading the file in specific page ranges.