Type conversion error - SQL query WHERE CLM IN LIST

Question

I have the following query which works fine when executed fine in SQL Mgmt Studio:

 

SELECT * FROM CMSDataViewer.dbo.RealTimeAgentData WHERE AgentID IN ('1937','1658','1608','1558','1640','1521') ORDER BY State, AuxReason, Time ASC

If I build out this query in C# it seems to be trying to be trying to convert the query value list to an int and fails when trying to read the results from the data reader:

 

using (SqlConnection connection = new SqlConnection(builder.ConnectionString))
                {
                    connection.Open();

                AgentQueryStart:
                    SqlCommand cmd = new SqlCommand("SELECT * FROM CMSDataViewer.dbo.RealTimeAgentData WHERE AgentID IN (@AgentIDList) ORDER BY State, AuxReason, Time ASC", connection);
                    cmd.Parameters.AddWithValue("@AgentIDList", AgentQueryParam);
                    dr = cmd.ExecuteReader();

                    while (dr.Read())
                    {
                        if (String.IsNullOrEmpty(dr[0].ToString()))
                        {
                            dr.Close();
                            goto AgentQueryStart;
                        }

                        //Construct list of data rows.
                        TimeSpan time = TimeSpan.FromSeconds(double.Parse(dr[5].ToString()));
                        ReturnData.Add(new AgentRealTimeDataRow(dr[0].ToString(), dr[1].ToString(), dr[2].ToString(), dr[3].ToString(), dr[4].ToString(), time.ToString(@"hh\:mm\:ss")));
                    }
                }

This fails at 'dr.Read()' with: System.Data.SqlClient.SqlException: 'Conversion failed when converting the nvarchar value ''1937','1658','1608','1558','1640','1521'' to data type int.'

 

If I add a breakpoint I can see that all variable values are as expected:

AgentQueryParam:  "'1937','1658','1608','1558','1640','1521'"

cmd.CommadText:  "SELECT * FROM CMSDataViewer.dbo.RealTimeAgentData WHERE AgentID IN (@AgentIDList) ORDER BY State, AuxReason, Time ASC"