Wikimedia Bugzilla is closed!

http://en.wikipedia.org/w/api.php?action=help&modules=query shows:

* action=query *
  Query API module allows applications to get needed pieces of data from the MediaWiki databases,
  and is loosely based on the old query.php interface.
  All data modifications will first have to use query to acquire a token to prevent abuse from malicious sites

This module requires read rights
Parameters:
  titles              - A list of titles to work on
  pageids             - A list of page IDs to work on
                        Maximum number of values 50 (500 for bots)
  revids              - A list of revision IDs to work on
                        Maximum number of values 50 (500 for bots)

The information about the maximum number is missing for the titles param.