It's no secret that Bob Carr long yearned to be Australia's foreign minister. The time, when it came, was short - just 18 months. Observers say that it was ultimately too short for former NSW premier to carve out a foreign policy legacy.

Carr names as his proudest achievements steering home Australia's successful bid for a seat in the United Nations Security Council and his successful lobbying of the international community to have sanctions against Myanmar lifted after the political reforms in that country.

His greatest regret by far was failing to win international support for his plan to improve medical care in the Syria conflict. Whatever disagreement there was internationally on how to end the intractable civil war, it should have been a no-brainer to protect medical workers and improve the supply of life-saving drugs.

"I promoted what I thought was a compelling proposition ... I argued it with every foreign minister I came into contact with," he said. "It was a case study in how hard it is to extract agreement from a neuralgic diplomatic wrangle."

In between those poles, Carr led the charge in challenging Julia Gillard's authority and securing Australia's abstention in the UN vote on Palestinian observer status. It was a shift he says Australia had to make.

"That [UN vote] was a hugely symbolic message - one of encouragement to Palestinians to take the peaceful path ... and a message to the Israelis that they were losing friends because of the vigorous expansion to the settlements on the West Bank."

On Indonesia and south-east Asia, Carr says his successor Julie Bishop "inherits a foreign policy that works" - stressing this is the hard work of successive governments.

And he says he was struck by the equally warm expressions of friendship he received both from Chinese and US leaders when he stood in for Kevin Rudd at the G20 meeting in St Petersburg just before the election. It underscored the fact that Australia is balancing its relationships well, and "won't have to choose" between the rival giants.

Experts say that as well as being short, Carr's tenure suffered from inhabiting the final quarter of an inconsistent and unpredictable period in foreign policy under the Rudd-Gillard governments. This made it all the harder to carve out a legacy.

Whereas it is possible to look back and see a foreign policy narrative under the Howard government with Alexander Downer in foreign affairs or the Hawke-Keating era with Gareth Evans, the same can't be said of the past six years, said Michael Wesley, Professor of National Security at the Australian National University.

"It was a bit all over the place," he said. "There was a lot of ambition but very little clear framework or strategy for how it would be put in place, and very little intellectual stitching between the elements."

Rory Medcalf, director of the international security program at the Lowy Institute, said that Carr made no lasting blunders. But nor did he have the time to embark on any long-term initiatives.

"He will struggle to leave a big impression on Australian diplomatic history," he said.

Both Wesley and Medcalf say that Australia should have taken a keener involvement in helping to ease tensions over territorial disputes between China and her neighbours in the South China Sea - a key shipping route that it is in Australia's interests to protect.

"I was disappointed that [Carr] was not more forthright on some of the big Asia issues like the South China Sea," Medcalf says. "Australia seems to be at pains not to stick its neck out for fear of offending China."