Sir Pudding (not actually knighted or pudding, sadly) asked about what the Ninja Tools advantage (DF12) covers.
Sir Pudding put together a good list, and I commented on which ones I think belong on it. I'm stealing it for here:
Arrow; $2 0.1 lbs. B276
Blowgun Dart; $0.1 .05 lbs ea. B276
Blowpipe Mount; $10 1 lb DF12 p. 15
Bow Drill; $8 1lb DF8 p. 25
Caltrops; $5 0.5 lbs DF1 p. 27
Door Needle; $4, neg. DF8 p. 25
Fukimi-bari; $5 .1 lbs DF12 14
Nageteppo, Flash; $40 .2 lbs DF1 p. 27
Nageteppo, Smoke; $40 .2 lbs DF1 p. 27
Shuriken, Star; $3 .1 lbs DF12 p. 14
Shuriken, Spike; $3 .1 lbs DF12 p. 14
Torch, Waterproof; $12 1b DF12 p. 15
Personally I'd have no issues having it include concoctions such as Bane poisons or Monster Drool. Why not? They aren't hideously lethal, they're certainly appropriate to the ninja's idiom, and they're within the realm of what seems like a gizmo. Here is that list, also courtesy of Sir Pudding:
Acid; $10 1lb DF1 p. 28
Anti-Toxin; $20 0.5 lbs DF 1 p. 28
Bane; $50 .5 lbs DF8 p. 37
Black Dust; $50 1 lbs DF8 p. 36
Foul Pepper; $50 1 lbs DF8 p. 36
Luminous Dust; $20 0.5 lbs DF8 p. 37
Monster Drool; $20 .5 lbs DF1 p. 29
Otherwise, I'd go with GM rulings on individual items. After all, if the GM and player both think a given item really fits the term "Ninja Tool" and otherwise is covered by the gizmo rules, it should be covered. And certainly a GM is within his or her rights to veto anything from the list above! But it's a good starting point at the very list.
(Oh and don't forget, Ninja Tools lets you trick out your weapons permanently. It's a powerful tradeoff for not having that one little piece of gear you really need . . .