Greetings,
I seem to recall that once upon a time the API requires all requests to be POST, but apparently GET is now allowed as well, and preferred for cachability. The API:Quick start page links to http://www.mediawiki.org/wiki/API:FAQ#GET_or_POST.3F, but apparently this link is broken and (as far as I can tell?) has never existed in the history. So two questions:
1) When was the change made, or has it been this way all along? 2) Is there are list of which operations require POST? Browsing through the docs, at least login and edit seem to, but is there a consolidated list? The Perl MediaWiki::API module suggests that GET is allowed only for query, logout, purge, and paraminfo.
Cheers, -jani