Mohammad Jabr, Visa on arrival is a TOURIST visa by its nature, with only difference that for the certain nationalities this tourist visa is available at the airport upon arrival, without applying in advance in their coutries.
But it is still TOURIST visa, and therefore it is illegal to work on the type of visa..
The only legal work visa for the short-term employment/consultancy/ internatioanl companies meetings and worksops, etc. is a BUSINESS visa.