Publish SVCB/HTTPS records under _agents.example.com so agents can discover your services from DNS, before any HTTP round-trip. Pair with DNSSEC so the answer is authenticated.
draft-mozleywilliams-dnsop-dnsaid — DNS for AI Discovery
RFC 9460 — Service Binding and Parameter Specification via the DNS (SVCB and HTTPS RRs)
RFC 4033 — DNS Security Introduction and Requirements