Add rate limiting for caching

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

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

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

No files, tests, or entry points are named. First clarify whether the task is rate limiting for caching, as the title says, or more descriptive authentication errors, as the body says; then locate the relevant paths and tests. The issue does not define what done looks like.

Written by the indexing model from the issue text.