A contract made in pursuance of RCW 36.64.010 shall fully set forth the amount of money to be contributed by each towards acquisition of the site and the improvement thereof and the manner in which such property shall be improved and the character of the building or buildings to be erected thereon. The contract may provide for the amount of money to be contributed annually by each for the upkeep and maintenance of the property and the building or buildings thereon, or it may provide for the relative proportion of such expense which such county and city shall annually pay. The contract shall specify the parts of such building or buildings which shall be set apart for the exclusive use and occupation of each.