Describe Harbor Action

Describe one granted operation and its currently available enabled fields. Select an identity from [List actions](../../../../../api-reference/harbors/actions/list). Supply its `connection_id`, `schema_id`, and `operation_id`. Use a scoped credential belonging to this Harbor; description does not require write access. `input_fields` contains only fields both explicitly granted by the administrator and currently available through the Connection. `lookup_fields` and `output_fields` describe the operation's lookup and output. Fields retain their types, constraints, required flags, and nullability. Supply exactly one lookup when `lookup_fields` is nonempty; otherwise omit it. Omitted input fields remain unchanged. Explicit null requires `nullable: true`. `idempotency` describes remote deduplication, not permission to retry. Output fields describe connector output; Harbor receipts remain metadata-only. A provider discovery failure or a granted operation that is no longer available returns `503 Service Unavailable`, not an empty field list. An ungranted identity returns `403 Forbidden`. These responses do not revoke saved permissions. Polytomic checks current grants and provider capabilities again at execution. Description fetches only the selected object's operations. It does not fetch fields for the entire catalog. Salesforce metadata may be cached for three minutes. Provider permissions and automation still apply. Send a new nonzero UUID in `X-Polytomic-Activity-Request-ID`. A supplied `X-Polytomic-Harbor-Session` must be active and bound to this credential and Harbor. Successful description is recorded as `action.listed`.