I'm not sure which part of PA you are located, but in Western PA, an actual 10-page written offer to purchase must be signed by the buyer before being presented to the seller. There were a few companies that were attempting to use "offer letters" a few years back, and they are simply not an acceptable method of making an offer to purchase in Western PA UNLESS they accompany the signed 10 page sales agreement.
Without more details, I can't be certain which method you are referring to. In addition, disclosures should be read and signed by the buyer before writing the offer, and a preapproval letter from the buyer's lender should accompany any offer.
Is your agent attempting to obtain disclosures and a preapproval letter on your behalf, so that your offer is solid when presented to the seller? Have you sat down with your agent to review \and sign the 10 pages of the sales agreement?