We’ve released the new service for agencies — the AgencyClients service for API version 5. This service allows advertising agencies to manage their clients.

You can use the get method. This method of the AgencyClients service returns a list of advertisers who are agency clients, their parameters, and settings for each advertiser‘s chief representative.

Please note:
For requests to this service:
In the Authorization header, specify the access token you received for the agency representative. Don't specify the Client-Login header. You can find more details about roles of Yandex.Direct users in the documentation.