Idempotency protects a workflow when a timeout leaves the caller uncertain whether an action completed. The agent or runtime can retry with the same operation key, while the receiving system recognizes the duplicate and returns the original result instead of applying the side effect again.
This matters for actions such as issuing refunds, creating records or sending commands. Idempotency requires stable request identities and durable outcome records; simply asking a model not to repeat an action does not provide the guarantee.
ELI5
Idempotency means repeating the same identified operation has the same intended effect as doing it once. It protects a workflow when a timeout makes the caller unsure whether the first attempt finished.
For example, an agent can retry a refund request with the same operation key, and the payment system returns the original result instead of issuing a second refund. The guarantee requires durable request identities and outcome records, not just a prompt asking the agent to be careful.
