Depends what the rent is. In the old days agents always asked for a 1 month fee called a finders fee from the tenant. This is illegal in the UK but I dont think it is illegal here.
Most agents get a fee from the owner equivalent to one month and as rentals are in abundance, most agents dont ask for any fee from the tenant, just the owner
However, you could refuse to pay it but if the property is what you want and it is a desirable property, then you may risk losing it to another rentor, so assuming its 50% or less than your monthly rent, its not unreasonable.
Some agents here are asking 50% of the monthly rent as their fee from the tenant.