Task: Text to Code
Input (English): What are the code and description of the least frequent detention type ?
Output (English): SELECT T1.detention_type_code ,  T2.detention_type_description FROM Detention AS T1 JOIN Ref_Detention_Type AS T2 ON T1.detention_type_code  =  T2.detention_type_code GROUP BY T1.detention_type_code ORDER BY count(*) ASC LIMIT 1