The school called his mother, who took him to the family doctor.
He was referred to Starship hospital for scans and observation of his mental health.
His parents are furious the school did not call 111 for their son who was described as changing colour to "purple red".
Principal Janine Irvine later told an external inquiry, ordered by the Education Ministry after the school did not hold an internal review, that seven adults were present that afternoon and none suggested an ambulance.
She said he recovered quickly to be able to walk and talk and appeared to be moving easily.
"There was just nothing we could see when we were observing him to suggest that he was in danger or pain. When I spoke with (the boy) I said: 'I see you've got a mark ... but he was oblivious," according to her written statement.
"I wanted to be as calm and professional as possible in what was an exceptional situation. Neither I nor any of the teachers in the school had ever experienced anything like this."
St John clinical director Dr Tony Smith told the external inquiry he would normally expect an ambulance to be called.
"I say this because the boy sounded like he was unconscious and blue when he was found."
However, Dr Smith said he understood why the staff did not call an ambulance as the emergency appeared to be over but noted the "case in question was most unusual".
The inquiry largely cleared Cornwall Park District School of any health and safety failings.
But the boy's mother said: "They didn't even do basic first aid checks on him. If this had happened in our own home, not the school, we'd have government agencies crawling all over the place.
"But in this case, there's nothing."
The couple are also disappointed about the lack of learning support leading up to the suicide attempt - in which he said he was trying to kill himself because school was "too hard" - despite them "pushing" for extra help to lift his academic achievement.
They had lobbied the school to provide extra learning support for their son who has attention deficit hyperactivity disorder, mild Asperger's, dyslexia, and anxiety disorders. He was on medication.
A teacher aide was available initially but this funding ended. The couple then struggled to get the school to provide an individual education plan, as recommended by his paediatrician, which led to a complaint to the board of trustees.
The Education Ministry inquiry focused only on the school's actions immediately after the suicide attempt - not what led up to it. However, it noted that an earlier complaint to the board by the boy's mother led to the school addressing allegations against staff rather than focus on her underlying concerns.
"There is no clear indication as to what caused the incident and it is not part of my brief to make any finding in that regard," said the report's author, Carol Anderson.
"Any such investigation would need to be a multi-party investigation involving the home, school and the relevant health professionals. No person has suggested to me that the school was responsible for the incident."
But in a country with the highest youth suicide rate in the world, the boy's parents cannot believe a wider investigation had not already happened.
The mother said she expected a review would include sitting down with the school, the Education Ministry and other agencies to ask why her son tried to commit suicide. "We're lucky he's alive. I thought we'd all be talking about how we [can] prevent this from ever happening again."
Management at Cornwall Park District School would not be interviewed but said in a statement that the suicide attempt was "an upsetting and sad time for all involved and the school has tried its best to meet the needs of the family".
"The school was not aware of all the risk factors leading up to this incident, with the psychologist who had been working with the family after the event noting this incident was 'out of the blue' and therefore could not have been expected to have been predicted by school staff with the information it had been provided with."
The boy's parents had signed a privacy waiver to allow the school to share relevant information with the Weekend Herald, but are unsure what is being referred to.
They say all this information would have been shared in an individual education plan for their son but this never occurred.
The couple also had concerns with the external review and spoke to their local MP, Sam Lotu-Iiga, who met the Education Ministry to request the case be looked at again.
Officials wrote back to say it was not appropriate.
Katrina Casey, the ministry's head of sector enablement and support said: "We believe the board has responded well to the parents' concerns and to the review."
Meeting notes obtained under the Official Information Act show the Education Ministry initially questioned why the school did not report the "serious" incident to the Department of Labour.
In response, the school felt there was no "serious harm" physically which is the reporting threshold.
But a spokesman for the Ministry of Business, Innovation and Employment - formerly the Department of Labour - told the Weekend Herald that the suicide attempt should have been reported since the test for "serious harm" was met if the child lost consciousness.
The boy's parents say he is now doing well at another school where he receives greater special education support.
Where to get help
• Youth services: (06) 3555 906
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (4pm to 6pm weekdays)
• Whatsup: 0800 942 8787 (noon to midnight)
• The Word
• Depression helpline: 0800 111 757 (24-hour service)
• Rainbow Youth: (09) 376 4155
• CASPER Suicide Prevention
If it is an emergency and you feel like you or someone else is at risk, call 111.
