For kun at få navne kan du bruge denne forespørgsel:
SELECT name
FROM sys.parameters
WHERE object_id = OBJECT_ID('YourProcedureName')
For at få mere detaljeret information (navn, type og længde af parameter):
SELECT p.name AS ParameterName, t.name AS ParameterType, p.max_length AS ParameterLength
FROM sys.parameters AS p
JOIN sys.types AS t ON t.user_type_id = p.user_type_id
WHERE object_id = OBJECT_ID('YourProcedureName')