You can use nxshell for that:
Code Select
from org.netxms.client.datacollection import DataCollectionConfiguration, DataCollectionObject
from org.netxms.client.objects import Node, Template
o = s.findObjectByName("Alexs-MBP")
config = session.openDataCollectionConfiguration(o.objectId)
for dc in config.items:
dc.description = dc.description + " - TEST"
config.modifyObject(dc)
config.close()