When I led self-serve at a usage-based data company, one of the most common feature requests was credit limits per API Key. People wanted to hand a key to a script, a teammate, or now an AI agent, and know it couldn't run up the whole bill. We get the same request at my current startup, Tanso.
Account-level and user-level limits exist — That's what enterprise quota systems are for. But they're heavy. For a startup there wasn't a simple drop-in. So I wrote one.
agentkey does four things:
Cap what a key can spend: A budget per key, per day or month
Scope what it can do: Least privilege per key
