> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lithtrix.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Error Codes

All errors use a consistent envelope:

```json theme={null}
{
  "status": "error",
  "error_code": "MACHINE_READABLE_CODE",
  "message": "Human-readable description."
}
```

| Code                   | HTTP | Description                                                               |
| ---------------------- | ---- | ------------------------------------------------------------------------- |
| `INVALID_API_KEY`      | 401  | Key missing or not recognised                                             |
| `RATE_LIMIT_EXCEEDED`  | 429  | Per-minute limit hit                                                      |
| `OVER_LIMIT`           | —    | Lifetime cap reached (returned in usage object, not as error HTTP status) |
| `AGENT_ALREADY_EXISTS` | 409  | Name + owner pair already registered                                      |
| `UPSTREAM_ERROR`       | 502  | Brave Search error                                                        |
| `SERVICE_UNAVAILABLE`  | 503  | Circuit breaker open                                                      |