Add rate limiting for import

**Problem**
When working with api, 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 mentions import, API error handling, and rate limiting but names no files, entry points, or tests. Start by locating the import API path and its existing error handling, then clarify the intended limits and message details before changing code. Done requires agreed rate-limit behavior and descriptive errors, with tests identified after the scope is clarified.

Written by the indexing model from the issue text.