According to the rules, when you attune to an item you form a bond with it. What does this entail, though?
For example, let's say a player wanted to steal an attuned magic item from someone. Would that person realize it's gone because of the bond? Would they know exactly where it was or who had it in their possession? Does this only apply if it's an intelligent item?
I realize that isn't laid out in the DMG (that I can find,) so it's probably up to discretion, but if other magic items specifically call out those properties, then it could be a "speaking from silence" sort of thing.
Attunement is first and foremost a game mechanic for limiting magic item use. You already found all the relevant rules and they explain what they mean by forming a bond (handling the item during a short rest) and what the benefits are (access to the item's magical properties.) There's nothing else to it.
If you're looking for a stronger story explanation, Sword Coast Adventurer's Guide provides one:
"Where a spell effect is brought to life by manipulating the threads of the Weave, the creation of a magic item ties some of those threads together in a specific way, to produce the desired effect for as long as the item lasts. ... In some cases, the magic of an item must be tied to its wielder, representing an entwining of the threads of the Weave between wielder and object known as attunement."
In the end it's still about getting access to the magic in the item.
"Some magic items require a creature to form a bond with them before their magical properties can be used. This bond is called attunement"
"A creature's attunement to an item ends if the creature no longer satisfies the prerequisites for attunement, if the item has been more than 100 feet away for at least 24 hours, if the creature dies, or if another creature attunes to the item."
"An item can be attuned to only one creature at at a time and a creature can be attuned to no more than three magic items at a time. Any attempt to attune to a fourth item fails; the creature must end its attunement to an item first."
Since a creature can only attune to three items at a time and it is a "bond" of some description, I would tend to play that a character is aware of their attunement status and whether they have any free slots open. I don't think the bond would necessarily offer any more than that based on RAW, though a DM could easily rule that it doesn't even provide that much information. Providing any more information than how many attunement slots are available to the character would again be a DM call.
The information that a character gets from being attuned to an item is:
Knowledge that they have attuned and are attuned to it.
What the item's effects are (but not always the specifics as in curses) including spells it can cast.
How many charges the item has.
And any other info the item description says the character learns.
So they only know where the item is if that is one of the effects of the item. Otherwise, they may not even realize it is missing until they lose the attunement.
Scenario: BBE has an attuned item in their foyer. PCs are in the foyer while BBE is busy upstairs (or possibly sleeping). A PC takes a short rest, in the foyer, to attune to the item.
The BBE would feel that their attunement break, and know on which item? (Likely resulting in angry BBE coming downstairs to check on where they know they placed the item.)
Scenario: BBE has an attuned item in their foyer. PCs are in the foyer while BBE is busy upstairs (or possibly sleeping). A PC takes a short rest, in the foyer, to attune to the item.
The BBE would feel that their attunement break, and know on which item? (Likely resulting in angry BBE coming downstairs to check on where they know they placed the item.)
If I'm not mistaken, there isn't a strict rule about that, but I'd say the creature should feel that the bond with the magic item was lost.
Of course, your DM might rule it differently.
EDIT: I realized other folks were also answering this in the thread.
According to the rules, when you attune to an item you form a bond with it. What does this entail, though?
For example, let's say a player wanted to steal an attuned magic item from someone. Would that person realize it's gone because of the bond? Would they know exactly where it was or who had it in their possession? Does this only apply if it's an intelligent item?
I realize that isn't laid out in the DMG (that I can find,) so it's probably up to discretion, but if other magic items specifically call out those properties, then it could be a "speaking from silence" sort of thing.
Attunement is first and foremost a game mechanic for limiting magic item use. You already found all the relevant rules and they explain what they mean by forming a bond (handling the item during a short rest) and what the benefits are (access to the item's magical properties.) There's nothing else to it.
If you're looking for a stronger story explanation, Sword Coast Adventurer's Guide provides one:
"Where a spell effect is brought to life by manipulating the threads of the Weave, the creation of a magic item ties some of those threads together in a specific way, to produce the desired effect for as long as the item lasts. ... In some cases, the magic of an item must be tied to its wielder, representing an entwining of the threads of the Weave between wielder and object known as attunement."
In the end it's still about getting access to the magic in the item.
The Forum Infestation (TM)
"Some magic items require a creature to form a bond with them before their magical properties can be used. This bond is called attunement"
"A creature's attunement to an item ends if the creature no longer satisfies the prerequisites for attunement, if the item has been more than 100 feet away for at least 24 hours, if the creature dies, or if another creature attunes to the item."
"An item can be attuned to only one creature at at a time and a creature can be attuned to no more than three magic items at a time. Any attempt to attune to a fourth item fails; the creature must end its attunement to an item first."
Since a creature can only attune to three items at a time and it is a "bond" of some description, I would tend to play that a character is aware of their attunement status and whether they have any free slots open. I don't think the bond would necessarily offer any more than that based on RAW, though a DM could easily rule that it doesn't even provide that much information. Providing any more information than how many attunement slots are available to the character would again be a DM call.
The information that a character gets from being attuned to an item is:
So they only know where the item is if that is one of the effects of the item. Otherwise, they may not even realize it is missing until they lose the attunement.
Scenario:
BBE has an attuned item in their foyer. PCs are in the foyer while BBE is busy upstairs (or possibly sleeping). A PC takes a short rest, in the foyer, to attune to the item.
The BBE would feel that their attunement break, and know on which item? (Likely resulting in angry BBE coming downstairs to check on where they know they placed the item.)
If I'm not mistaken, there isn't a strict rule about that, but I'd say the creature should feel that the bond with the magic item was lost.
Of course, your DM might rule it differently.
EDIT: I realized other folks were also answering this in the thread.