Mathematical model describing the action of a narrow tillage tool was used to analyse the effect of selected soil and tool parameters on that action. Working resistance and the indices of soil deformation (critical depth, cracking angle) were investigated. Working resistance of a narrow tool was affected mostly by the soil internal friction angle and less by the soil cohesion and bulk density and increased with the rise of considered soil parameters. The cracking angle rose with the soil cohesion only while it decreased with increasing other soil/tool parameters. Critical depth increased with internal friction angle and cohesion of the soil and it decreased with rising of the other factors.