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# required

The model must call one or multiple tools.

```
static let required: GenerationOptions.ToolCallingMode
```

## Discussion

[`LanguageModelSession`](/documentation/FoundationModels/LanguageModelSession) keeps calling tools until a tool throws an error from its
[`call(arguments:)`](/documentation/FoundationModels/Tool/call(arguments:)) method or you change the mode dynamically using a
[`LanguageModelSession.DynamicProfile`](/documentation/FoundationModels/LanguageModelSession/DynamicProfile).

---

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