Tool / tool call

Two things in one entry, because you always meet them together. A tool is a capability handed to an AI: search the web, read this file, look up a customer, send an email. A tool call is one use of one of them — one search, one email.

The drill and the hole. The tool is what's in the van. The tool call is the hole you drilled at half past ten on Tuesday.

You have already watched this happen. When ChatGPT pauses mid-answer to search the web, read a file you attached, or work out a sum, those are tool calls. It isn't a developer-only idea — it's the thing you see every time an answer comes back with a source attached.

Why it matters: an AI's list of tools is its job description and its risk profile in one. Reviewing what an agent actually did means reading its tool calls — the actions it took — rather than its own confident summary of itself. Those two are not always the same story.

Related: Function calling · Agent