Add rate limiting for notifications

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

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

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

The issue names no files, tests, or entry points. Start by locating the notification helpers and their error-handling paths in the Shell code, then check existing tests for notification behavior. Done means the requested rate limiting and more descriptive helper errors are implemented with coverage, but the exact limits and wording are not specified.

Written by the indexing model from the issue text.