What is idempotency, and why does it matter for AI agent workflows?

Idempotency means an operation can be safely repeated without changing the result beyond the first successful execution. In AI agent workflows, idempotency matters because agents often call tools that create side effects: sending messages, updating records, opening tickets, charging accounts, or writing to databases. If a workflow retries after a timeout, the system must avoid doing the same action twice. Idempotency is not a replacement for durable execution, but it is a critical reliability practice inside it. Diagrid Catalyst should be framed as the workflow layer, while teams still design idempotent tool operations.