{"name":"onyx_agent_verify","tier":"metered","price_usdc":"0.10","endpoint":"https://onyx-actions.onrender.com/v1/onyx_agent_verify","method":"POST","input_schema":{"type":"object","properties":{"target":{"type":"string","description":"The agent to verify: its A2A endpoint URL, or its /.well-known/agent-card.json URL, or its base origin."}},"required":["target"]},"description":"Signed agent liveness + authenticity oracle. Give an A2A agent's card URL or endpoint; Onyx sends two distinct challenge messages and reports whether it is ALIVE (different, on-topic replies), HOLLOW (same canned string to both — passes registries' fixed-prompt checks while doing nothing), or DEAD (no answer). Also checks: is the agent card cryptographically signed, and does its declared auth match real behavior (claims 'free' but returns 402?). Ed25519-signed verdict. Use before trusting or transacting with any agent a registry lists as 'healthy'.","when_to_use":"Before trusting, listing, or transacting with an agent — verify it is a real live agent and not a hollow template that canned-answers registry health checks. Also to audit an agent directory for fake/dead listings.","vs_alternatives":"Registries (a2aregistry, Bazaar) only check reachability with a fixed prompt a canned agent passes; they cannot tell alive from hollow, don't verify the card signature, and don't reconcile declared auth vs behavior. This sends two distinct challenges to expose canned responders, checks the signature, and returns a signed, recomputable verdict.","example_request":{"target":"https://example-agent.com/.well-known/agent-card.json"},"example_response":{"ok":true,"verdict":"hollow","trust_score":20,"probes":{"replies_identical":true},"detail":"Returned a byte-identical canned reply to two different challenges."},"settle_to":"0x3fD9ee1373562f894D322B37DFFAd7a5D2b2d78f","network":"base","facilitator":"https://facilitator.xpay.sh","payment_required":true,"free_introspection":true,"note":"GET this URL = free introspection card. POST with x402 payment header to call."}