This function is implemented by FrameXML in FrameXML/FriendsFrame.lua.

Determines if the player can cooperate with another player character

canCooperate = CanCooperateWithToon(toonID);

Arguments

toonID 

number - determined from the 5th return of BNGetFriendInfo(friendIndex)

Returns

canCooperate 

boolean - true if and only if the toon represented by the toonID is on the same realm and faction as the player