Key Takeaways
- Wait-for-OTP agent flow: after send_otp, wait for the human (or your channel) — do not hammer send_sms until a code appears in chat.
- Prefer webhook/event to the backend; agents should poll challenge status, not the radio.
- Not a first-party Cursor/Claude plugin. Your orchestration sits on a REST SMS wrapper.
- Priced by devices and SMS send volume. You use your own phone and operator SMS credit. Waiting does not pause operator billing on messages already accepted.
- Free 300 SMS lifetime: one impatient agent can finish it in a lunch break.
- Pair with send/verify tool concepts; Developer Center owns send payloads.
Concepts for a wait-for-OTP agent flow stop chatty models from double-sending login codes. Overview: MCP overview. Send & verify tools. MCP specification.
Priced by devices and SMS send volume. You use your own phone and operator SMS credit.
“Wait” means wait for the user or your status API — not invent another SMS every time the model feels impatient.
Send → wait → verify
1) send_otp with Idempotency-Key. 2) Tell the user to check SMS. 3) verify_otp on their input. Optional: surface send accept / device health, never plaintext codes. Docs: Developer Center.
Wait strategies that do not spam
| Strategy | OK? | Note |
|---|---|---|
| User-driven verify | Yes | Default for login UX |
| Poll challenge status | Yes | Your DB: pending / expired |
| Block tool on DLR | No | Ties up MCP; radio may lag |
| Resend every N seconds | No | Burns airtime + locks users out |
What you may poll
Challenge TTL, attempt count, device last-seen. For delivery events use webhooks, not a chat sleep.
Not an agent product SKU
Wait-for-OTP is an orchestration pattern you write. SMS Gateway remains devices + volume on BYO Android and carrier credit — not a first-party IDE agent marketplace.
When wait must stop
Expired TTL, max attempts, stale device, empty airtime. Map failures with error-handling concepts.
Overview vs this spoke
Rate limits: safety. Multi-tenant isolation: multi-tenant concepts.
Checklist
- Hard TTL on wait.
- No timed resend without user action.
- Idempotent send.
- Verify on user input.
- Device health checked once, not every second.
- Airtime + plan volume monitored.
Next steps
Rehearse a full login with a charged phone offline mid-wait, then size devices + SMS volume.
Related product pages
Jump to the live product docs for this topic—not another long-form article.
- OTP and 2FA SMS on AndroidAuthentication flows
- SMS API documentationLive endpoint reference
- device and SMS volume pricingPlans and allowances
- Android SMS gateway product guideDefinition, product, and how to buy
