On fives, I prefer narrower string spacing, like the 17.5mm on my G&L M-2500, and its tone (and that of the L-2500) would definitely work for Tool-like material. The MFD pickups have massive punch and grind, even the slightly underwound versions in the M-series.
Since you mention issues with reaching the lower strings, fretboard radius might be an important spec for you, as it is for me. I prefer flatter fretboards largely because there's less of a "hump" to reach over to access the lower strings. I'm very happy with the 12" radius board on my G&L, but on fives would gladly go flatter, and Yamaha makes some very flat fretboards. The TRBX505 and BB series fives have a 23.625" radius, which I've liked when I've tried them. I think their string spacing is slightly wider than my G&Ls, but I was comfortable with it.
The easiest reach to lower strings, I suspect, would be a narrow nut, narrow string spacing, and a relatively flat fretboard. Great fretwork, possibly with Plek fret leveling, would also help with this. I'm not sure which basses would provide the optimal blend for you, and of course other specs matter too, like the necks's rear profile and whether the fretboard edges are nicely rounded. So it's best to test as others have said, but you might be able to eliminate some that have more rounded fretboards, which I think of as those with less than a 12" radius (though I believe MM is 11" which feels about the same).