diff --git a/t4_devkit/dataclass/box.py b/t4_devkit/dataclass/box.py
index b558089..0c9cedd 100644
--- a/t4_devkit/dataclass/box.py
+++ b/t4_devkit/dataclass/box.py
@@ -151,6 +151,11 @@ def __eq__(self, other: Box3D | None) -> bool:
 
     @property
     def size(self) -> SizeType:
+        """Return the box size in the order of (width, length, height).
+
+        Returns:
+            (width, length, height) values.
+        """
         return self.shape.size
 
     @property
@@ -175,7 +180,7 @@ def corners(self, box_scale: float = 1.0) -> NDArrayF64:
             First four corners are the ones facing forward. The last four are the ones facing backwards,
                 in the shape of (8, 3).
         """
-        length, width, height = self.size * box_scale
+        width, length, height = self.size * box_scale
 
         # 3D box corners (Convention: x points forward, y to the left, z up.)
         x_corners = 0.5 * length * np.array([1, 1, 1, 1, -1, -1, -1, -1])
diff --git a/t4_devkit/dataclass/shape.py b/t4_devkit/dataclass/shape.py
index 0617119..83d21b1 100644
--- a/t4_devkit/dataclass/shape.py
+++ b/t4_devkit/dataclass/shape.py
@@ -39,6 +39,11 @@ def from_name(cls, name: str) -> Self:
 class Shape:
     """A dataclass to represent the 3D box shape.
 
+    Attributes:
+        shape_type (ShapeType): Box shape type.
+        size (SizeType): Box size in the order of (width, length, height).
+        footprint (Polygon): Polygon of footprint.
+
     Examples:
         >>> shape = Shape(
         ...     shape_type=ShapeType.BOUNDING_BOX,
@@ -62,7 +67,7 @@ def _calculate_footprint(size: SizeType) -> Polygon:
     """Return a footprint of box as `Polygon` object.
 
     Args:
-        size (SizeType): Size of box ordering in (length, width, height).
+        size (SizeType): Size of box ordering in (width, length, height).
 
     Returns:
         Footprint in a clockwise order started from the top-right corner.