An agent's manifest should indicate in some way whether it is capable of acting as a Convener. That means it can send "invite", "uninvite", "grantFloor" and "revokeFloor" events and it knows what to do when it receives "requestFloor", "declineInvite", "bye", "publishManifests" and "yieldFloor" events.
It seems that the most logical placeto indicate this would be a field in the "capabilities" section, since it is a capability, not part of the identification. Maybe add a new field for "conversationalCapabilities" or "floorSupport".