在Microsoft bot FormFlow上显示描述而不是索引

[Serializable]
public class MyForm
{
    public string description;
    public string answer;

    public MyForm()
    {
        var builder = new FormBuilder<MyForm>();
        var form = builder
            .Field(nameof(description), validate: ValidateDescription)
            .Build();

        Description = "请描述您的问题：";
    }

    public static IForm<MyForm> BuildForm()
    {
        return new FormBuilder<MyForm>()
            .Message("欢迎使用表单！")
            .Build();
    }

    private static Task<ValidateResult> ValidateDescription(MyForm state, object response)
    {
        var result = new ValidateResult();

        if (string.IsNullOrWhiteSpace((string)response))
        {
            result.IsValid = false;
            result.Feedback = "问题描述不能为空，请重新输入。";
        }
        else
        {
            result.IsValid = true;
            result.Value = response;
        }

        return Task.FromResult(result);
    }
}