currently there is no permanent way to allow or deny tools by group.
You CAN do it with ULX though.. but it requires modifying the tool's init.lua file with
if !ply:query("toolname") then
ULib.tsay(ply, "You are not allowed to use this tool", true)
return false
end
ply could be anything that the tool uses for the player entity.. usually ply, pl, or p
you would need to put this under the left click and the right click functions.
also.. then you'd need to add "toolname" to the group's allows in groups.txt