According to p.341 TAG troopers have maximum range of nine hexes for the TAG, but I can't find any information about their TAG short/medium/long range brackets or any construction information like TAG weighs, costs, tech level etc. I assume they use the same values as the Battle Armor Light TAG from TW/TM, but it should probably be clarified in TO.
Edit: You may also want to look at a related thread started by Daryk (
http://bg.battletech.com/forums/index.php?topic=55725.0). I've compared the statistics for Battle Armor Light TAG (pp. 204-305 TW, 298 TM, 247-248 TM), with the statistics of TAG Light (Man-portable) from AToW (p. 275 AToW), and I think they are almost the same device (theit cost is the same, for example). The Battle Armor version is heavier, but that may be due to the way it is attached to the Battle Armor and possibly shielded from damage or hostile environments.
If it is indeed the case then it should answer my question about range brackets for TAG troopers (3/6/9, as I suspected), and possibly also Daryk's questions about a possible error in one of the books (although I'm not entirely certain if ranges from TW should always translate directly into AToW, so it is not a definite answer for me).