T · Token · tool use

Tool use

A model calling external functions / APIs as part of its reasoning.

In one sentence

Tool use is the capability of a language model to call external functions, APIs or services during its reasoning step — looking up real data, performing actions, or chaining computations beyond what its weights know.

When it matters

When an answer depends on live data (current ticket, stock level, weather) or on an action (book the visit, create the ticket).

A real-world example

helpcode Hotline uses tool-use to look up the caller’s CRM record before answering — so the agent knows the warranty status without asking.

Curated by helpcode research team · Last reviewed 2026-05-22