In my community, many application of Tool Belt are told and I introduce some of them.

Practical applications:

• Twice usage of sloted/exhausted tools in single slot: Put two tools, one in play area and the other attached in Tool Belts. After trigger first one, swap it with that in Tool Belt and use one more.
  • Example: Lockpicks, Mariner's Compass, Riot Whistle...
• Fight/Investigate flexiblity for tools: Unlike other classes, some of tool is (two-handed) weapon. When you need to fight, use tool weapon; when you need to investigate, use tool for investigator.
  • Tool weapon: Chainsaw, Sledgehammer...
  • Tool for investigation: Old Keyring, Flashlight, Mariner's Compass, Magnifying Glass ...
• Keeping sacrificial asset: After fully uses of supplies (or any other), attach that asset into Tool Belt and throw it away when you meet asset-hate encounter such as Crypt Chill.
  • Rule note: you still can choose the card attached into Tool Belt because 1) it is still asset 2) you still have the control of it 3) it is still in play. (not official ruling, but my interpretation)
  • Old Keyring: If you investigate using Old Keyring with 1 key, you can attach that at during the investigation test. Nevertheless, the test works normally and the last key is removed from that Old Keyring; however, attached Old Keyring is not discarded because the text box is alread blanked so that the effect "If there are no keys on Old Keyring, discard it" does not work. If you want to discard that Old Keyring for some reason, you simply detach it, and then that is discarded. (my rule interpretation)

Funny(?) applications:

• We can make charged Old Keyring with keys having some secrets (in the Tool Belt), since the "Uses (2 keys)" is blanked. Of course, we should distinguish them even if same resource tokens are placed. After that Old Keyring is detached, it's not clear that the charge and secret could remain on it :)
• Attaching Quickdraw Holster with .32 Colt: We could attach Quickdraw Holster thanks to the existance of the Devil from Observed. Then, .32 Colt in Quickdraw Holster now regain hand slot in the Tool Belt :)
• Discarding (non-slot?) tool card: The common way to discard the asset is using the slot limit, but we cannot do this for non-slot asset so that it's hard to discard non-slot asset. Now, if we want to discard non-slot tool, just attach Tool Belt and then discard (or Sleight of Hand) Tool Belt. Is it really useful? Not yet, because non-slot tool is Darrell's Kodak only when I write this review.

One issue I have with this card is, that it does not seem that great for Tool-cards, that occupy double slots.

Let's say, Kymani has a Sledgehammer in the tool belt, and a Thieves' Kit and their Grappling Hook in play. If they want to use the hammer, they can swap one of the two assets in play into the belt, but have to discard the other one. Unless, they have somehow a way to gain a third hand slot. Currently, while not all "Scarlet Keys" cards have been spoiled yet, the only option for them for a third slot would be Quickdraw Holster, which clashes with the body slot of the belt, and would be of no use for Tool-assets anyway.

An interaction, that might be good, but I don't see that many applications, where it's amazing, could be Well Prepared. Cards attached are still in play, and their icons not blanked, so this should work. I doubt, you would want to use the icons from Chainsaw or Sledgehammer on other weapons, but the passive from a Lantern might be worth it, if you ever want to flex Yorick or (more likely) Tommy. Also, sometimes a single pip can make a difference.

QUESTION:

If I swap out Flash Light with 1 charge left on it into the Tool Belt -- when I bring Flashlight back out to use does it have all all its charges again?

Or would it come out with the same number of charges it had when it went into the Tool Belt?

I was trying really hard to find a neat combo with Kymani Jones's deckbuilding options and Tool Belt, since the last expansion (maybe the previous ones too, but I haven't played the game too much prior to The Scarlet Keys) seems to have hard-to-find interactions that are both quite strong and very fun to discover and play (e.g. demolishing enemies with Gray's Anatomy, Ancient Stone and Empirical Hypothesis, you can look this up in my review of Gray's Anatomy), and I think I've found something interesting. It is not necessarily tied to Kymani at all, but I think it works especially well in some of her builds.

The idea is all about the interaction between Tool Belt and Pocket Multi Tool that allows to bypass the "Limit 1 per investigator" text on the latter. First we play one of our Pocket Multi Tools and Tool Belt, then, when we have our second Pocket Multi Tool in hand, we attach the first one to Tool Belt and play the second one, which as far as I understand becomes possible because the text on the first copy is blanked, including the "Limit 1 per investigator" line. Then we can activate the first Multi Tool in our hand and once it exhausts switch it with the Multi Tool attached to the Tool Belt to get another activation during the same round. It also works with the Spring-Loaded upgrade, but you won't be able to use both Multi Tools during the same test. This neat trick, given that we have some upgrades on the Multi Tool, lets us get two Unexpected Courages every turn (or even two free copies of Lucky!). As I've mentioned, this works very well in a Kymani Jones deck that aims to utilize Chuck Fergus, Crafty and Pilfer to grab 3 clues for one action every turn, because two instances of +2 to skill value from two copies of Pocket Multi Tool should be more than sufficient to succeed by 2 on the Pilfer test to get it back at the end of the turn. Another reason why it is very good in Kymani is how Pry Bar upgrade can single-handedly protect them from nasty treacheries, bringing their already above average (for a rogue, naturally) to a confident 5 or even 7, if necessary.

There are definitely a lot of investigators that benefit greatly from having two Pocket Multi Tools in play, and I'm sure other deckbuilding enthusiasts will mention the most interesting combinations in the comments. I'll just say that interactions like this is what makes Arkham deckbuilding discoveries so exciting.

EDIT: As it was noted in the comments, this trick does not actually work :( I'll still leave the post here, hopefully to spark the spirit of discovery to find another way to get around that pesky "Limit 1 per investigator" line.

Question: Tool Belt blanks the text box of the attached asset. The "Limit 1 per Investigator" is part of Pocket Multi Tool's text box. You should be able to attach 1 and have another one unattached in play so you can use one, then swap them and use the other one.