What it means
The model emits structured calls (name + arguments) that your app executes, then feeds results back into the conversation for the next step.
Why designers should care
Show tool name, scope, arguments summary, success/failure, and let users deny or undo, especially for write actions.
Example
A calendar agent proposes “Create 30-min hold tomorrow 2pm”; the UI previews event details and requires tap-to-confirm before the createCalendarEvent tool runs.
Common mistakes
- Running write tools silently with no preview or audit trail.
- Tool errors surfaced as generic model failures.
- Too many tool calls in one turn with no progressive disclosure.
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Frequently asked questions
What is Tool Use?
Tool use is when a model invokes external functions (search, calculators, APIs, code runners) to go beyond plain text generation.
Why should designers care about Tool Use?
Show tool name, scope, arguments summary, success/failure, and let users deny or undo, especially for write actions.
What are common mistakes with Tool Use?
Running write tools silently with no preview or audit trail; Tool errors surfaced as generic model failures; Too many tool calls in one turn with no progressive disclosure.