You could have a machine-readable 'contract' for bots.That would set out what was allowed (in fact, almost nothing, so it might be a little pointless (but you could have a section of the site - the 'bot pen' where they could peddle their wares)) and what wasn't allowed (almost everything, but including posting in new threads).
(
The Alchemist king of the needlessly complicated,
Sat 1 Nov 2008, 10:35,
archived)