Short Definition
Tool use lets an AI system call external functions, APIs, databases, or software actions instead of only generating text.
Intuition
The model decides when it needs outside capability, then the system executes a tool and feeds the result back.
Technical Definition
Tool-use systems expose structured actions to a model or controller, validate arguments, execute calls, and incorporate observations into subsequent reasoning.
Example
A travel assistant calls a flight search API before recommending options.
Common Misunderstandings
Tool use does not remove the need for permissions and validation.
The tool result can be correct while the final model response is still wrong.