Nato has "done something" in Kosovo - it has escalated a government-terrorist conflict into a major catastrophe.
The text of the Rambouillet plan shows the level of diplomacy that took place. Rambouillet insisted on a Nato force, not an "international" one. It also insisted that Nato have free unrestricted access to the whole of Yugoslavia, not just Kosovo (article 8) including free access to airspace, roads, ports and other facilities. It would also grant Nato complete immunity from legal processes for any acts it may commit during the occupation (article 6).
When, hardly surprisingly, Yugoslavia refused to sign this agreement, our leaders decided that bombing must commence and so must the predictable humanitarian catastrophe. Clearly, this is not diplomacy, it is politics by ultimatum.
We can "do something". We can exhaust all diplomatic and peaceful means to resolve a conflict before we escalate the violence. A glance at Rambouillet gives the lie to the claim that "talking hasn't worked".