Purpose
The discovery file answers the question: where do I start?
A caller arriving at an unfamiliar system needs a lightweight place to begin. The discovery file can identify the protocol, expose the service's self-awareness, and list the important public routes without forcing the caller through an entire contract document on first contact.
That makes the file useful both for first-touch automation and for human orientation.
Service declaration
The file announces that the system is prepared to expose richer contract information through AIXE patterns.
Public route list
It directs the caller toward the routes that matter rather than acting as a full protocol encyclopedia.