Hi @Gijs,
You can’t ask for tasks at the workspace level (it’s potentially too big of a firehose of data).
Above the project level, you can only filter in one of the following ways:
"resource_type": "workspace_membership", "action": "added""resource_type": "workspace_membership", "action": "removed""resource_type": "team_membership", "action": "added""resource_type": "team_membership", "action": "removed""resource_type": "project", "action": "added""resource_type": "project", "action": "removed""resource_type": "project", "action": "deleted""resource_type": "project", "action": "undeleted""resource_type": "project", "action": "changed"