Pigeon: Signed passes stop AI sub-agents from overstepping their authority

Pigeon, a signed Pass for what a sub-agent may do

Pigeon is an open-source Python library that lets developers hand a sub-agent a signed, narrowed credential—a Pigeon Pass—instead of copying the parent's API key. The Pass specifies exactly which actions the agent may perform on which resources, with constraints like rate limits. Verification returns detailed denial reasons, and delegation prevents privilege escalation. It integrates with MCP middleware and works without a central server.