On an offer, if it is made to the agent then they are legally bound to report it to their client. This is not conditional on you viewing the property.
As a Chartered Surveyor, I always make clear to a resi agent that I know this fact as I know what they are like!
If they do not report the offer then there is options available to you.
Always make an offer in writing, subject to contract and any other conditions that you feel are necessary.