Consider deprecating old services API

**Problem**
When working with services, the error messages could be more descriptive.

**Suggestion**
Improve error handling and add detailed error messages.

**Context**
This would help with debugging and maintenance.

Start by locating the old services API and reviewing its current error handling. The issue does not name files, entry points, or tests, so first clarify which API is affected and what deprecation behavior and error-message detail are expected. Done should include an agreed deprecation path and corresponding error-handling changes.

Written by the indexing model from the issue text.