The ornamental design for the hair tool holder, as shown and described.
FIG. 1 is a front perspective view of the hair tool holder;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a back elevation view thereof;
FIG. 4 is a right side elevation view thereof;
FIG. 5 is a left side elevation view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines showing the interior surface and openings in FIGS. 1,2 and 6 and the back cover in FIG. 3, are for illustrative purpose only used to illustrate portions of the hair tool holder that form no part of the claimed design.