Webhook Polling vs. a Temporary Inbox for AI Agents
Compare direct webhooks, polling, queues, and temporary webhook inboxes for agents that pause while waiting for an outside event.
Short answer
Use provider polling when the provider exposes durable status and request volume is acceptable. Use your own queue for guaranteed internal delivery. Use a temporary inbox when an agent needs a short-lived callback URL and later retrieval without operating a permanent public webhook service.
The failure this prevents
Agents are often not running when a payment, export, signing request, or background job completes. A callback sent directly to a sleeping process is lost unless another durable component receives it.
Recommended workflow
- Determine whether the source supports polling, callbacks, or both.
- Define how long the workflow can wait and how many events may arrive.
- Choose whether delivery must be durable and guaranteed or merely short-lived and retrievable.
- Authenticate and validate the meaning of every event before acting.
- Delete temporary inboxes and close abandoned workflows.
Working starting point
curl https://api.scrubmytext.com/v1/signals/create \
-H "Authorization: Bearer smt_live_YOUR_KEY" \
-H "Content-Type: application/json" \
-d '{"label":"order-82731","expires_in_seconds":3600,"max_events":5}'Relevant product: CatchMySignal · REST + MCP
Reproducible example
An export completes while the agent is asleep
An agent starts a report export that may take twenty minutes, creates a one-hour callback inbox, gives the callback URL to the export service, and exits. The workflow resumes later and retrieves the bounded event list.
- Expected behavior
- The temporary inbox lets the resumed workflow discover that a callback arrived without running a permanent public receiver. Before downloading or publishing anything, the agent validates the event or polls the export provider’s authoritative status. Expired or full inboxes fail closed.
- What it teaches
- Convenient receipt is not guaranteed delivery or sender authenticity. A durable queue is the better primitive when loss, ordering, replay, and backpressure are requirements; polling is simpler when the provider already exposes authoritative state.
Production verification checklist
- Test callback arrival before and after the agent process exits.
- Exercise duplicate, late, unauthenticated, oversized, and over-capacity events.
- Confirm the workflow checks provider state before a consequential follow-up action.
Decision rule
CatchMySignal is a temporary event inbox, not a guaranteed message queue. If losing an event is unacceptable, use a durable queue or the provider’s authoritative status as the final source of truth.
Good fit
- An agent needs a callback URL for a bounded workflow.
- The agent may resume later and retrieve what arrived.
- Operating a permanent webhook endpoint would be disproportionate.
Use another approach when
- You require guaranteed ordered delivery and replay.
- The payload contains sensitive data that should not enter a temporary third-party inbox.
- The provider already offers simple, authoritative polling that meets your latency needs.
Options compared
| Option | Strength | Important limitation | Best fit |
|---|---|---|---|
| Polling | Simple and authoritative when supported | Latency and repeated requests | Provider status APIs |
| Direct webhook | Low latency | Requires an always-available receiver | Permanent applications |
| Durable queue | Delivery controls and backpressure | Infrastructure and operations | Critical internal events |
| CatchMySignal | Disposable callback URL plus later retrieval | Bounded retention and no queue guarantee | Temporary agent workflows |
Implementation cautions
- Treat the webhook URL like a temporary password.
- Validate event authenticity separately when the sender supports signatures.
- Retrieve provider state before a consequential action when the event is only a notification.
Frequently asked questions
Does a temporary inbox verify the sender?
No. Use a signed-signal verification step or confirm state with the provider.
Is this a message queue?
No. It is deliberately bounded and temporary.
When should I poll instead?
When the provider exposes authoritative state and the desired latency and request volume make polling simpler.
How this guidance was reviewed
The product behavior described here is checked against ScrubMyText's public OpenAPI contract and automated contract tests. The worked example is synthetic and contains no customer data. Recommendations separate verified product behavior from broader implementation judgment, and every limitation remains visible rather than being converted into a marketing claim.
Related decisions
Next step
Use the product page for exact limitations and access requirements, then copy the corresponding REST or MCP workflow.