Mo. Rev. Stat. § 535.020
Whenever any rent has become due and payable, and payment has been demanded by the landlord or the landlord's agent from the lessee or person occupying the premises, and payment thereof has not been made, the landlord or agent may file a statement, verified by affidavit, with any associate circuit judge in the county in which the property is situated, setting forth the terms on which such property was rented, and the amount of rent actually due to such landlord; that the rent has been demanded from the tenant, lessee or person occupying the premises, and that payment has not been made, and substantially describing the property rented or leased. Giving the notice provided in section 441.060 is not required prior to filing a statement or obtaining the relief provided in this chapter. In such case, the clerk of the court shall immediately issue a summons directed to such tenant or lessee and to all persons occupying the premises, by name, requiring them to appear before the judge upon a day to be therein named, and show cause why possession of the property should not be restored to the plaintiff. The landlord or agent may, in such an action for unpaid rent, join a claim for any other unpaid sums, other than property damages, regardless of how denominated or defined in the lease, to be paid by or on behalf of a tenant to a landlord for any purpose set forth in the lease; provided that such other sums shall not be considered rent for purposes of this chapter, and judgment for the landlord for recovery of such other sums shall not by itself entitle the landlord to an order for recovery of possession of the premises. The provisions of this section providing for the filing of a statement before an associate circuit judge shall not preclude adoption of a local circuit court rule providing for the centralized filing of such cases, nor the assignment of such cases to particular circuit or associate circuit judges pursuant to local circuit court rule or action by the presiding judge of the circuit. The case shall be heard and determined under the practice and procedure provided in the Missouri rules of civil procedure, except where otherwise provided by this chapter.
§ 535.020, RSMo