In api/v1/swagger/definitions/patron.yaml are defined patron fields. api/v1/swagger/paths/patrons.yaml defines fields that can be used as filter. There are some fields missing : middle_name pronouns date_renewed privacy_guarantor_fines overdrive_auth_token anonymized Patron definition also contains those but I'm not sure they can be added as filter : extended_attributes checkouts_count overdues_count account_balance library