The data hierarchy is too complex for the client Lack of validation of returned data Lack of request authentication No indication of return field types The request returns redundant data that does not meet the client's requirements Lack of server-side filtering support

The listed problems indicate shortcomings in API design or data exchange systems:

• Complex data hierarchy complicates understanding and processing data on the client side. The solution is to simplify the structure, using flat or more logical models.

• Lack of validation for returned data leads to errors and inconsistency. Data validation should be implemented on the server before sending.

• Absence of request authentication is a serious security gap. Authentication mechanisms (e.g., OAuth, API keys) need to be implemented.

• No indication of return field types makes working with data on the client side more difficult. Data schemas (e.g., JSON Schema, OpenAPI) with clear type descriptions should be used.

• Redundant data in responses results in excessive traffic and load. It is necessary to implement selection of only necessary fields (projection) or use request parameterization.

• Lack of server-side filtering forces the client to load and filter large volumes of data, which is inefficient. Support for filters on the server should be added.

In summary, to improve the API, it is necessary to:

• Define and document clear data schemas.
• Implement authentication and authorization.
• Implement data validation.
• Optimize data structure and the volume of returned information.
• Add support for filtering and sorting parameters on the server.