An air carrier Captain reported the Gate Agent delivered an incomplete final document release to the flight crew at pushback. The Captain directed the agent to locate the missing document and deliver it to the flight prior to pushback.

Narrative

When I arrived at the gate; I asked the Gate Agent about specials and she informed me of a lithium-ion battery powered wheelchair being boarded. I thanked her and said I would be awaiting the device tag. She politely acknowledged and I went down the jetway. Once boarding was completed a different Gate Agent delivered the final reconciliation to the flight deck. They asked if we were good to close and I said I needed the device tag to the wheelchair. The gate agent smirked and rolled his eyes at me; and said that it was on the wheelchair and that it had been loaded already. I told him that I needed the copy and he flippantly said that he would get it. His demeanor was disrespectful and implied to me that he had never heard of this procedure before and that I was incorrect. He returned to the flight deck with the form and I showed him the FOM page X.XX.X and told him that for future reference we needed this tag as it is notification of dangerous goods. He again was dismissive and disrespectfully replied yeah; ok" and left the flight deck."