> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.simz.com/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.simz.com/_mcp/server.

# Errors and Rate Limits

> Understand common Lead Receive API errors and retry behavior.

Lead Receive API errors use standard HTTP status codes and machine-readable `code` values where available.

## Common errors

| Code                  | HTTP status | Meaning                                                               |
| --------------------- | ----------- | --------------------------------------------------------------------- |
| `AUTH_FAILED`         | `401`       | Missing, invalid, or expired API key.                                 |
| `INVALID_REQUEST`     | `400`       | Request body or lead format is invalid.                               |
| `AGENT_NOT_FOUND`     | `404`       | Agent does not exist, is inactive, or does not belong to the company. |
| `RATE_LIMIT_EXCEEDED` | `429`       | Too many requests for the agent.                                      |
| `INTERNAL_ERROR`      | `500`       | SimZ could not complete the request.                                  |

## Retry guidance

Retry `429` only after the indicated delay. Retry `5xx` with exponential backoff. Do not retry validation errors until the request is corrected.