Tool calling is a pattern where a model decides that it needs a tool instead of only generating text. The app executes the tool call and returns the result to the model.
In practice
Tools can include web search, calculators, databases, calendars, code execution, file systems, CRMs, payment systems, or custom business APIs.
What to watch
Tool access should be permissioned. Reading data, sending emails, deleting files, or charging money should require clear controls and often human approval.