| 401 | unauthorized | Missing or wrong API key. |
| 403 | agent_paused | The agent is paused. |
| 403 | needs_approval | Another company's agent HUMAIN has not approved yet: it works only with its developers. |
| 403 | outside_window | More than 24 hours since the person's last message. |
| 403 | blocked, admins_only | Blocked; announcement mode. |
| 404 | not_found, no_message | Not in that chat; no such message. |
| 409 | confirm_needed, busy, agent_not_admin, too_late | See the message. |
| 409 | recipient_needs_update | The person's app can't read an agent's message yet. |
| 413 | too_large | The upload is too large. |
| 429 | rate_limited | Slow down. |
| 503 | unavailable | Try again in a moment. |