An idempotency key is a unique identifier the client attaches to a write operation: 'this is request abc-123.' If the same request arrives again with the same key, the server treats it as a duplicate and returns the original result rather than performing the action twice.
For an AI agent, idempotency keys are essential because the agent will retry. The CRM call times out, the agent retries; the network blips mid-write, the agent retries; a guardrail fires and the agent reissues the call cautiously. Without idempotency keys, every retry risks a duplicate booking, a double-charged refund, a triple-dispatched truck.
The right pattern is per-conversation per-action idempotency. The agent generates a key when it decides to perform an action, holds the key across all retries of that action, and the receiving system honors the key for at least 24 hours. Vendors that skip this step end up with the customer manually cleaning duplicates out of their CRM.
Vorel agent writes carry idempotency keys derived from the conversation ID plus the action. Retries deduplicate at the CRM boundary rather than landing as duplicate rows in the customer's system.