To fix the 400 error, remove or update any assistant hooks referencing the deleted tool. In your assistant configuration, look for hooks like this and delete or update them:

json
{
  "on": "call.ending",
  "do": [
    {
      "type": "tool",
      "tool": {
        "type": "function",
        "toolId": "57cf24b7-1c85-4062-ad0c-327400a2aa25" // <-- Remove or update this
      }
    }
  ]
}

Go to your assistant's hooks section in the dashboard, find any references to the deleted tool ID, and remove or replace them to resolve the error. For more details, see the [assistant hooks documentation](https://docs.vapi.ai/assistants/assistant-hooks). Source: - [Assistant hooks documentation](https://docs.vapi.ai/assistants/assistant-hooks)

Hi, Please let us know if you have this error again.