We claim the ornamental design for a tool for a vacuum cleaner, as shown and described.
FIG. 1 is a bottom perspective view of a tool for a vacuum cleaner showing our new design;
FIG. 2 is a top perspective view;
FIG. 3 is a front view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a side view thereof;
FIG. 6 is a side view of the opposite side of FIG. 5;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
The long dash-dot-dashed lines represent boundary lines. The boundary lines and the details shown in short dashed lines form no part of the claimed design.