{
  "unit": "page",
  "credits_per_page": 1,
  "pages": 480,
  "total": 480,
  "available": 4952,
  "committed": 48,
  "sufficient": true,
  "rate_source": "standard",
  "note": "Fixed price: 1 credit per page of a graded copy at the standard rate. Failed, cancelled and unreadable copies are free."
}

{
  "error": {
    "code": "invalid_api_key",
    "message": "The API key is not valid.",
    "request_id": "req_4f9c2a7e1b3d4c8a9e6f0b2d5a7c1e3f"
  }
}

{
  "error": {
    "code": "insufficient_scope",
    "message": "This API key lacks the evaluation:write scope.",
    "request_id": "req_4f9c2a7e1b3d4c8a9e6f0b2d5a7c1e3f",
    "details": {
      "required_scope": "evaluation:write"
    }
  }
}

{
  "error": {
    "code": "not_found",
    "message": "The resource was not found.",
    "request_id": "req_4f9c2a7e1b3d4c8a9e6f0b2d5a7c1e3f"
  }
}

{
  "error": {
    "code": "validation_failed",
    "message": "questions[0].max_marks is required.",
    "request_id": "req_4f9c2a7e1b3d4c8a9e6f0b2d5a7c1e3f",
    "details": {
      "errors": [
        {
          "field": "questions[0].max_marks",
          "code": "required",
          "message": "max_marks is required."
        }
      ]
    }
  }
}

{
  "error": {
    "code": "rate_limited",
    "message": "Too many requests. Retry after 2 s.",
    "request_id": "req_4f9c2a7e1b3d4c8a9e6f0b2d5a7c1e3f"
  }
}