C# - ADO.NET - Call SQL Server Stored Procedure

Program.cs

namespace MyDbTest
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(DBHelper.Greet("Frodo", "Baggins"));
        }
    }
}

class DBHelper
{
    public static string Greet(string name, string surname)
    {
        using (var connection = new SqlConnection(ConfigurationManager.ConnectionStrings["MyDb"].ConnectionString))
        {
            using (var command = new SqlCommand("Greet", connection))
            {
                connection.Open();

                command.CommandType = CommandType.StoredProcedure;

                command.Parameters.Add(new SqlParameter("@Name", SqlDbType.NVarChar)
                {
                    Value = name
                });
                command.Parameters.Add(new SqlParameter("@Surname", SqlDbType.NVarChar)
                {
                    Value = surname
                });
                command.Parameters.Add(new SqlParameter("@Message", SqlDbType.NVarChar)
                {
                    Direction = ParameterDirection.Output,
                    Size = Int32.MaxValue
                });

                command.ExecuteNonQuery();
                return command.Parameters["@Message"].Value.ToString();
            }
        }
    }
}

StoredProc_Greet.sql

CREATE PROCEDURE [dbo].[Greet]
	@Name NVARCHAR(MAX),
	@Surname NVARCHAR(MAX),
	@Message NVARCHAR(MAX) OUT
AS
BEGIN
	SET @Message='Hello ' + @Name + ' ' + @Surname +'.How are you?';	
END