Mo. Rev. Stat. § 431.070: Contracts with counties, effect.

All notes, bonds, bills, contracts, covenants, agreements or writings made whereby any person shall be bound to any county, or to the inhabitants thereof, or to the governor, or to any other person, in whatever form, for the payment of money or any debt or duty, or the performance of any matter or thing, for the use of any county, shall be valid and effectual to vest in such county all the rights, interests and actions which would be vested in any individual, in any such contract made directly to him.