Why do exports need checking in the Black Sea Grain Initiative?

In the Black Sea Grain Initiative, grain ships going to and from Ukraine are inspected in Istanbul for the presence of unauthorised cargo such as weapons. On the 3rd of August, 2022, a first ship was authorised to export grain from Odessa (Ukraine) to Tripoli (Lebanon) after inspectors had confirmed there were no weapons on the ship.

Why is the agreement concerned with inspecting ships that leave Ukraine for weapons? I can understand that Russia in particular is concerned that grain ships heading to Ukraine are not secretly carrying weapons, but it would be surprising for a country under attack to secretly export weapons.