AFAIK the tooltip is automatically configured to reflect the Related Action's "description". So the first thing to try (if i'm right) would be to clear out the related action's Description field.
Sorry [mention:b45a4f6a20b14a008e4e0ec732a8bf98:e9ed411860ed4f2ba0265705b8793d05] . I missed your reply. Hence, I replied [emoticon:7001ca6adc474a82b3fba88f98f15573]