(1)    General requirements. No claim shall be allowed unless it is in writing, describes the nature and amount thereof, if ascertainable, and is sworn to by the claimant or someone for the claimant that the amount is justly due, or if not yet due, when it will or may become due, that no payments have been made thereon which are not credited, and that there are no offsets to the knowledge of the affiant, except as therein stated. If the claim is one for which property is available under s. 859.18, the claim shall describe which classification under s. 766.55 (2) is applicable to the claim. The claim shall also show the post-office address of the claimant. The presumption under s. 766.55 (1) applies to the classification of claims for which property is available under s. 859.18.

   (2)   Requirements when claim founded on written instrument. If a claim is founded on a written instrument which is available, the original or a copy thereof with all endorsements must be attached to the claim.