---
title: ToolChoiceViolationError
description: Learn how to fix AI SDK ToolChoiceViolationError
---

# ToolChoiceViolationError

This error occurs when a `generateText` response does not satisfy an enforced
tool choice. It is thrown when `toolChoice` is set to `'required'` but the
response contains no structured tool call, or when a specifically selected tool
was not called.

The error does not automatically interpret text or reasoning as an executable
tool call. You can inspect `content` to implement opt-in recovery, including
schema validation before executing any recovered call.

## Properties

- `toolChoice`: The effective tool choice that the response did not satisfy
- `finishReason`: The reason why the model finished generating the response
- `provider`: The provider that returned the response
- `modelId`: The model that returned the response
- `content`: The normalized content returned by the model
- `message`: The error message

## Checking for this Error

You can check if an error is an instance of `ToolChoiceViolationError` using:

```typescript
import { ToolChoiceViolationError } from 'ai';

if (ToolChoiceViolationError.isInstance(error)) {
  const serializedCall = error.content.find(part => part.type === 'text')?.text;

  // Parse and validate serializedCall before treating it as a tool call.
}
```