The Tasks API only supports Creating, Updating, and Deleting (POST, PUT, & DELETE). It does not support GET retrieval.
Please add this functionality so we can replicate Task filters via the API.
+1 - this is kind of a weird oversight. Why is there not GET endpoint? The tasks within the ticket object are just ID/URL - no name, no completed value. Really need to be able to access those for the app we're building!
In case anyone else ends up here, there is an undocumented GET endpoint in the API: /incidents/{incidentID}/task/{taskID} will get you ALL of a given task's data, including its completion state. This is still a little suboptimal as it means iterating over every task per incident and doing an API lookup for each one ... but it does work. It would certainly be nice if we could get ALL Tasks by incident ID so we're only doing a single API hit per incident, rather than one for every task.