Job letter from the company in Oman?

I hope you all are doing well.
I have certain doubts regarding job visa.
I have applied for a post of electrical engineer in oman petroleum company through agency.the agent asked me to submit the required amount inorder to process the application.but when i asked him whther he will give me any letter he told me that oman company does not offer job letter and directly give u visa.
The question is,does the company offer job letter or any sort of letter before the visa??