| ”I don’t have an agentsim tool” | MCP not connected or config not loaded | Verify the config file path, confirm its syntax is valid, and restart your client |
| ”Authentication failed” or 401 error | Missing or incorrect API key | For hosted HTTP, send an active key in x-api-key. Codex CLI uses env_http_headers; launch it from the terminal that exports the key. Only local stdio servers use an env block |
| Connection refused or timeout | Wrong transport type | Ensure your client is using HTTP transport, not SSE — the /sse endpoint does not exist |
wait_for_verdict stops before its requested wait ends | Client tool timeout is shorter than the SMS wait | In Codex CLI, set tool_timeout_sec = 150 for a 120-second wait. After a timeout, check the app result and release your session; do not automatically send another SMS |
pool_exhausted error | No number was available | Check the status page and try later. Repeated allocation attempts do not resolve availability |
409 conflict on open_challenge | The Gather Agent Line is already assigned to an active challenge | Use list_numbers to inspect your sessions. Close a session only if you created it for this test and it is no longer needed; otherwise wait for capacity |
| Client reports a missing MCP session ID | Client expects stateful Streamable HTTP | Use a client version that supports stateless Streamable HTTP; the hosted endpoint does not issue mcp-session-id headers |
406 Not Acceptable from curl | Missing Accept header | Add -H "Accept: application/json, text/event-stream" to every curl request |
