MBeanFeatureInfo:  Parent class from which all other metadata objects inherit
a name and a description string.

MBeanOperationInfo: Describes and operation:the return type, the signature
as an array of parameters,and the impact(whether the operation just returns
information or modifyies the resource)

MBeanConstructorInfo: Describes a constructor by its signature;

MBeanParameterInfo: Gives the type of a parameter in an operation
or constructor signature;

MBeanAttributeInfo: Describes an attribute:its type,whether it is
readable,and whether it is writable.

MBeanNotificationInfo: Contains an array of notification type strings.


From Sun Docs.