UN Weapons Inspectors Mandate?

To determine whether or not Chemical weapons were used.

That and that alone - They were specifically forbidden by the UN to apportion blame on either side for the attack.

So they went to Damascus
Visited the site of the attack
Collected forensic samples
Visited hospitals
Interviewed Doctors and patients

OK tell me what else they were allowed to do by the Syrian Authorities?
Any visits to Syrian Army Chemical storage sites?
Any samples of Syrian Army Chemical warfare agents for comparison?
Any explanation of the delay in allowing the inspections in the first place?

The Syrians did this before after the Israelis with the help of the Turks destroyed it's secret nuclear weapons site - the Syrians delayed allowing IAEA inspectors in while they sanitized the place - didn't work as the instrumentation brought in still detected nuclear particles that could not be naturally explained.