Function name does not conform to the required pattern: Only letters, numbers, underscores, or hyphens are allowed, with a maximum length of 64 characters.

To fix the 400 status error caused by the invalid tool name multi_tool_use.parallel, you can take the following steps:

• Ignore Invalid Tool Calls: If the model generates an invalid tool call, ignore the response and resend the request.

• Avoid Nested Calls: Ensure that the model is not trying to invoke nested calls that could result in invalid tool names.

• Validate Tool Names: Before processing tool calls, validate them against the expected pattern (^[a-zA-Z0-9_-]{1,64}$) to filter out invalid names.

• Update API Handling: If possible, suggest to OpenAI that they update their API to handle recursive multi_tool_use.parallel calls properly.

By following these steps, you can mitigate the issue caused by the model's hallucination of invalid tool names.