Items and tags
Your items are your stuff. They go in your inventory. Playing cards, bundles of rope, your trusty blade-- it might have tags to describe its use, or it might simply be a flavorful item that may or may not have specifically codified effects.
How much can your inventory hold?
There's not a strict limit to what you can have in your inventory-- your inventory should be able to hold everything you need, but it probably should still make sense. Unless your setting calls for a reason otherwise, it's generally assumed that you have a backpack, sapient pearwood luggage, or other inventory-management item with you to carry what you need. When in doubt, it's practical to not limit what can be in someone's inventory. Nobody wants to deal with explaining how exactly they're carrying twelve different swords in their backpack.
You can have as many things as you want to have in your inventory, but you can only benefit from what's equipped. Equipped items are things you're wearing, holding, have on your belt-- anything that you know exactly where it is and can grab it immediately in a pinch. Just like what's in your inventory, what you have equipped should make sense. Whenever you have the opportunity, often with downtime but it can be as flexible as your GM would like, you can equip and unequip items.
When you're in an action scene you can use anything you have equipped without taking any time to pull it out or put it away. If they're not equipped, then you'll have to take at least one action to retrieve the items and equip them first. Your GM may say you must use multiple actions if you're trying to get out a lot of things, what you're trying to get needs assembly after being retrieved, or what you're getting is particularly difficult to get out of your portable storage. You can unequip any items necessary for what you have equipped to still make sense as a part of these actions.
Similarly, if you wish to stow items for any reason in an action scene you can take at least one action to unequip them into your inventory. Just like with equipping, if it's something cumbersome or something that requires disassembly before storage your GM may say you must use multiple actions for this.
Tags describe what's important about an item: how it can be used, what benefits it provides, and anything else that matters. You can only benefit from an item's tags if it's equipped.
Not every item has tags or needs them. If it's obvious how an item is used, it probably doesn't need a tag or, if it does, you can tag it in the moment. Sometimes items don't need tags until they're used in a specific way that you want to remember. In short, tag things when they need to be tagged.
This is especially true for narratively important tags. An iron sword doesn't need to be tagged with iron when an adventurer picks it up, but as soon as they face something vulnerable to the metal, it should be.
Using Items Improperly
If you Attack with something that doesn't have the weapon tag, Defend with something that doesn't have the shield tag, or do something else to use an item in a way that it's not intended to be used, your GM may say there is an additional risk that the item might be damaged, destroyed, or otherwise lost and/or some tags on the item do not apply. A +5 sword might be very good at attacking, but there's no guarantee that it'd be equally as good at blocking.
Here's a suggested list of tags that you can use to describe the items in your game. Be sure to add more tags that are important to your setting! If you're in a dark fantasy setting hunting beasts of the night and need silvered weapons to confront them, silver should be a tag. If you're in a futuristic dystopian setting and everything legally acquired is monitored through a chip, unchipped should be a tag.
+1, +2, +3, ...
Items with this tag are more effective than other items of the same type due to exemplary craftsmanship, materials, and/or renown. Add the tagged number to any test you make with this item. If the item's tags grant the wearer a passive value (such as armor HP), add the tagged amount.
Items with this tag are often light, compact, or rely on manual precision to operate effectively. Bows, scimitars, sniper rifles, and pistols often have the Agility tag.
requires: any attribute tag
Items with this tag are wearable defense like personal shield generators, Kevlar vests, or full plate. When worn, armor grants the wearer with additional armor hp equal to the highest passive value of the item's tagged attributes. A character can only benefit from one set of armor at a time.
Items with this tag is often heavy or strenuous to operate effectively. Mauls, axes, grenade launchers, and shotguns often have the Brawn tag.
Items with this tag are small and easy to take out or hide. Daggers, miniature crossbows, pistols, and brass knuckles often have the Concealable tag.
requires: a tag like Pyromancy or Telekinesis that indicates what kinds of special abilities it's for
An item with this tag is a tool that helps you with your special abilities, like a wand for a wizard or a nyanobot array for a genetically engineered cat doctor. Pairs well with the +X tag to give you +X on tests you make with that special ability.
Items with this tag are often foreign or complicated in inconsistent ways, requiring keen adaptability to operate effectively. Alien technology and mental magic focuses often have the Intuition tag.
Items with this tag are often complicated and only able to be effectively operated by someone thoroughly trained in how it works. Mad science gadgets, ancient rituals, and physical magic catalysts often have the Knowledge tag.
Items with this tag require two hands to wield effectively. Rocket launchers, mauls, longbows, and staves often have the Large tag.
Items with this tag might be sentient and require reasoning with to operate effectively or otherwise somehow utilize the wielder's social aptitudes. A high maintenance combat support robot, a tape recording of the maddening snores of C'thulhu, or an arcane book of physically manifesting insults might have the Presence tag.
[Close, Short, Medium, Long] Range
The distance at which the item is able to be effectively used. Primarily used for weapons, but also useful for things like grappling hooks and ladders to represent their reach. Items can have many range tags -- if an item isn't tagged with a specific range, it's not useful at that distance.
requires: At least one attribute tag
Items with this tag are carriable defense, like bucklers, directional forcefields, and riot shields. Equipping a shield allows you to Defend with the tagged attribute.
requires: At least one attribute tag AND at least one range tag
Items with this tag are anything used to Attack another character, from table legs to semi-automatic rifles. While equipped with a weapon, you can Attack with one of the tagged attributes at one of the tagged ranges.
Items with this tag might be painful to operate or otherwise require and amplify the mental fortitude required to get them to work. A shard of broken glass, a covenant magic catalyst, and alien biotech integrated into a human might have the Will tag.