One of the important properties that attributes in management systems typically have is, when they represent metrics, to say whether they are gauges or counters.  We should reflect this in the conventional Descriptor fields.  The proposal is to add this to the table in javax.management.Descriptor:

Name        Type    Used in
metricType  String  MBeanAttributeInfo, MBeanOperationInfo

Meaning
The type of a metric, one of the strings "counter" or "gauge".  A metric is a measurement exported by an MBean, usually an attribute but sometimes the result of an operation.  A metric that is a counter has a value that never decreases except by being reset to a starting value.  Counter metrics are almost always non-negative integers.  An example might be the number of requests received.  A metric that is a gauge has a numeric value that can increase or decrease.  Examples might be the number of open connections or a cache hit rate or a temperature reading.