When using verbatim string literals prefixed with @, it means that the enclosed string is treated as literal. So basically no backslash '\' escaping. To escape double quote ("), just double it ("").
string jsonStr = @"[
{""name"": ""Obj1"", ""description"": ""Test description..."", ""url"":""http://www.test.com"" },
{ ""name"": ""Obj2"", ""description"": ""Testing..."", ""url"":""http://www.test.com"" },
{ ""name"": ""Obj3"", ""description"": ""Welp..."", ""url"":""http://www.test.com"" }
]";