Mo. Rev. Stat. § 429.080
It shall be the duty of every original contractor, every journeyman and day laborer, including persons who use rented machinery or equipment in performing such work or labor, and every other person seeking to obtain the benefit of the provisions of sections 429.010 to 429.340, within six months after the indebtedness shall have accrued, or, with respect to rental equipment or machinery rented to others, then, within sixty days after the date the last of the rental equipment or machinery was last removed from the property, to file with the clerk of the circuit court of the proper county a just and true account of the demand due him or them after all just credits have been given, which is to be a lien upon such building or other improvements, and a true description of the property, or so near as to identify the same, upon which the lien is intended to apply, with the name of the owner or contractor, or both, if known to the person filing the lien, which shall, in all cases, be verified by the oath of himself or some credible person for him.
§ 429.080, RSMo