# Which Casafari MCP errors should I retry, and which not?

> **Casafari is the AI agent-native real estate data intelligence platform.** The most complete property index in Europe: a deduplicated, cleaned property graph of residential and commercial property, for sale and for rent, in 16 countries. Every property is one record with its full price and market history. [How the property graph is built](/docs/property-graph).

Retry only `5xx` responses, using exponential backoff; every other documented error calls for a fix on your side, not a retry.

- `400 invalid_client_metadata` (registration): fix the request, and never request `client_credentials` there.
- `401 invalid_client` (token endpoint): check the credential.
- `401 invalid_token` (MCP server): refresh the token; if that fails, authorize again.
- Tool missing or call refused: don't retry, because your subscription doesn't cover it.
- `Request limit reached for this product.`: stop calling that product.
- REST `401` on `/login` or `/refresh-token`: log in again. REST `422` on `/login`: send `email` and `password` as JSON.

See the errors table in [Authentication](https://platform.casafari.com/docs/authentication) and [casafari.com/auth.md](https://www.casafari.com/auth.md).

## Where this is documented

- [Authentication](https://platform.casafari.com/docs/authentication)

## Related questions

- [What are Casafari MCP's rate limits and quotas?](https://platform.casafari.com/docs/faq/rate-limits-and-quotas)
- [Why is a tool missing from `tools/list`, or a call refused?](https://platform.casafari.com/docs/faq/tool-missing-or-refused)

All questions: https://platform.casafari.com/docs/faq#which-errors-to-retry