Parts of the CBD were closed as police were called but Mr Tupou climbed down the crane of his own accord after about half an hour.
He was taken to hospital amid concerns he had no recollection of how he got to the top of the crane.
Appearing in court on Tuesday his lawyer revealed blood tests showed he had methamphetamine and a high level of alcohol in his system.
"I'm told it was as much a surprise to him that he'd done it [climbed the crane] as it was to those on the ground," defence lawyer Aaron Kernaghan said.
The lawyer said Mr Tupou was embarrassed by his behavior and the surrounding media coverage and would accept full responsibility.
He will now be assessed for community service work as per the order of the Magistrate and will return to court on March 16.
- nzherald.co.nz