agentless datasync create-location-object-storage requires --agent-arns

[ThomasMorrow-SOI]

Unclear if this is an issue with my use case, but we are trying to run datasync to pull from GCS to AWS S3, agentless via CLI. The command I am using is

aws datasync create-location-object-storage --server-hostname storage.googleapis.com --server-protocol HTTPS --server-port 443 --bucket-name MYBUCKET --subdirectory /MYDIRECTORY --access-key GCS_ACCESS_KEY_ID --secret-key GCS_SECRET_ACCESS_KEY --region us-east-1

but this returns
aws: error: the following arguments are required: --agent-arns

It's my understanding that since May 2025 agentless datasync is possible, and documentation for create-location-object-storage lists --agent-arns as optional. Something missing here?