FIG. 1 is a front perspective view showing a “handle for tool” incorporating the design of my invention; FIG. 2 is a top view thereof; FIG. 3 is a bottom view thereof; FIG. 4 is a side view thereof, FIG. 5 is another side view thereof; FIG. 6 is a front view thereof; FIG. 7 is a rear view thereof; FIG. 8 is a front perspective view showing the handle shown in FIG. 1 residing in a different tool thereof; FIG. 9 is a top view of the tool shown in FIG. 8; FIG. 10 is a bottom view of the tool shown in FIG. 8; FIG. 11 is a side view of the tool shown in FIG. 8; FIG. 12 is another side view of the tool shown in FIG. 8; FIG. 13 is a front view of the tool shown in FIG. 8; FIG. 14 is a rear view of the tool shown in FIG. 8; FIG. 15 is a front perspective view showing the handle shown in FIG. 1 residing in a different tool thereof; FIG. 16 is a top view of the tool shown in FIG. 15; FIG. 17 is a bottom view of the tool shown in FIG. 15; FIG. 18 is a side view of the tool shown in FIG. 15; FIG. 19 is another side view of the tool shown in FIG. 15; FIG. 20 is a front view of the tool shown in FIG. 15; FIG. 21 is a rear view of the tool shown in FIG. 15; FIG. 22 is a front perspective view showing the handle shown in FIG. 1 residing in a different tool thereof; FIG. 23 is a top view of the tool shown in FIG. 22; FIG. 24 is a bottom view of the tool shown in FIG. 22; FIG. 25 is a side view of the tool shown in FIG. 22; FIG. 26 is another side view of the tool shown in FIG. 22; FIG. 27 is a front view of the tool shown in FIG. 22; and, FIG. 28 is a rear view of the tool shown in FIG. 22. The “handle for tool” shown in phantom lines depicts the environment of my new design and forms no part of the design of my invention.