Prototypically, an Agent intentionally applies the Instrument with the purpose of achieving a result:
Less prototypically, the action could be unintentional:
The key is that the Instrument is not sufficiently “independently causal” to instigate the event.
However, to downplay the agency of the individual operating the instrument, the instrument can be placed in a passive by-phrase, which construes it as the instigator:
Note that the examples in #004 can be rephrased in active voice with the Instrument as the subject.
This includes some expressions which incorporate the Instrument in a noun:
Conversely, roadways count as Paths but can be construed as Instruments:
An entity that facilitates an action by applying intermediate causal force.