In HBASE-4991 review comments (https://reviews.apache.org/r/3917/), Todd was commenting about Accumulo's FATE framework.
It will be good to have a command in shell to find the status of online schema change, delete_region (HBASE-4991) and other master-coordinated tasks.
Master/RS WebUI shows monitored tasks for master-coordinated tasks. In a production environment with 100s of RS, it will be handy to run a command from shell and get the status as we do track the state in ZK for each task. Thanks.