The code looks mostly well-written, but there's one issue that needs improvement: the exception handling for invalid calls to get_model might not be sufficient for all cases.

Improvement Suggestions:

1. Ensure Proper Error Handling: Add checks after calling get_model() to verify if model is not null or returns an error value before attempting to invoke it. This can help prevent unexpected failures from unhandled errors.

   def is_valid(self, model_type: str, model_name, model_credential: Dict[str, object], model_params):
       # Ensure proper model retrieval and initial validation
       model = provider.get_model(model_type, model_name, model_credential, **model_params)
       if model is None:  # Handle case where model retrieval fails
           raise AppApiException(ValidCode.model_not_found.value,
                                gettext('Model not found'))
   
       try:
           res = model.invoke([HumanMessage(content=gettext('Hello'))])
          # Print response for debugging purposes (optional)
       except Exception as e:
           raise AppApiException(ValidCode.valid_error.value,
                               gettext('Verification failed, please check whether the parameters are correct: {error}')
                                   .format(error=str(e)))
   
       return True

By adding these modifications, you improve robustness by checking if the model was successfully retrieved before proceeding with other operations, which can reduce runtime exceptions due to missing models. Also note that using None here is more precise than relying on truthiness for provider.get_model() responses.