Modo 14.0v2 docs:

Using Sculpting Brush Tools

Sculpting is a fast and intuitive method for building and refining 3D models. The brushes for sculpting can be found in the Paint layout interface, where Modo has a collection of tools and useful commands that are dedicated to painting and sculpting. You can also access the tools from the Texture > Sculpt Tools menu. Invoking any of the tools displays the associated properties in the appropriate viewport panel.

To sculpt, you need to select both a tool (a brush) and a tip (designates how the tool affects the geometry). When working with a mouse, drag over the surface to apply the stroke. You can also use a pressure-sensitive stylus and tablet. To scale the size of the brush tip, right-click and drag in the viewport.

Sculpting Tools
	Push	Moves vertices away from the surface along the calculated normal direction of the polygon.
	Inflate	Pushes all vertices out along their normals with the push strength modulated by the brush.
	Fold	Creates a "hill-and-valley" effect by pushing vertices at the center of the brush in and pulling vertices at the edge of the brush outward.
	Clay	Raises the surface along the normal of the underlying polygons up to a desired level.
	Smooth	Evens out bumpy and irregular surfaces.
	Carve	Pushes the surface inward to create a valley.
	Scar	A pinch operation combined with a brush tip that pushes and pulls at the geometry, leaving a specific mark that looks like a scar.
	Flatten	Massages the mesh to a common flat plane.
	Smudge	Pulls vertices along with the brush briefly and then leaves them to rest as the brush passes on.
	Move	Grabs the mesh inside the brush and drags the surface in the direction of the brush.
	Tangent Pinch	Pulls the geometry in towards the axis perpendicular to the brush stroke.
	Center Pinch	Pulls geometry in towards the center of the brush.
	Spin	Creates a vortex of vertices around the center of the brush.
	Emboss	Moves the surface of the mesh that is within the brush at the time of the click in or out along the local normals.
	Attenuate	Image-based sculpting only. Diminishes the strength of the sculpted data stored in the current displacement or vector displacement image texture.

Sculpting Masks
	Mask: Paint	Adds masking to the target surface.
	Mask: Smooth	Softens or blurs an existing mask.
	Mask: Scale Down	Decreases the strength of the target mask.
	Mask: Erase	Removes masking from the target surface.
	Mask: Set Value	Applies the defined value to the mask to overwrite all existing values.