Cloudflare Cloudflare This document describes a JSON based format for clients using [DIRECTORY] to advertise information about themselves. This document describes a JSON-based "Signature Agent Card" format for signature agent using [DIRECTORY] to advertise metadata about themselve. This includes identity, purpose, rate expectations, and cryptographic keys. It also establishes an IANA registry for Signature Agent Card parameters, enabling extensible and interoperable discovery of agent information.