Jquery - WebMethod Returning JSON But The Response Obj In $.ajax() Callback Is Only A String

public class JsonBuilder
{
private StringBuilder json;
public JsonBuilder()
{
json = new StringBuilder();
}
public JsonBuilder AddObjectType(string className)
{
json.Append(""" + className + "": {");
return this;
}
public JsonBuilder Add(string key, string val)
{
json.AppendFormat(""{0}":"{1}",", key, val);
return this;
}
public JsonBuilder Add(string key, int val)
{
json.AppendFormat(""{0}":{1},", key, val);
return this;
}
public string Serialize()
{
return json.ToString().TrimEnd(new char[] { ',' }) + "}";
}
}

Here is the Web Method [WebMethod]

public static string GetPersonInfo(string pFirstName, string pLastName)
{
var json = new JsonBuilder().AddObjectType("Person");
json.Add("FirstName", "Psuedo" + pFirstName).Add("LastName", "Tally-" + pLastName);
json.Add("Address", "5035 Macleay Rd SE").Add("City", "Salem");
json.Add("State", "Oregon").Add("ZipCode", "97317").Add("Age", 99);
return json.Serialize();
}................