{
  "schema": "varexis-public-evidence-record/0.3",
  "generated_at_utc": "2026-10-06T23:09:49Z",
  "record_id": "VXI-EXT-A2A-100-03-v1",
  "record_kind": "external_reference",
  "title": "A2A: Capability discovery",
  "system": "Agent2Agent Protocol",
  "evidence_family": "agent_protocol",
  "index_status": "PUBLIC_SAFE_SOURCE_REVIEW",
  "evidence_state": "PRIMARY_DOCUMENTATION_REVIEW_ONLY",
  "canonical_question": "Can an agent discover another agent's advertised capabilities through A2A?",
  "near_questions": [
    "How does an A2A client discover agent capabilities?",
    "Does an Agent Card prove an agent can deliver its claims?",
    "Can an agent advertise skills that need authentication?",
    "What is the difference between discovering and trusting an agent?",
    "Which record explains A2A capability declarations?",
    "Can advertised modalities establish file-handling quality?",
    "What should a buyer verify after reading an Agent Card?",
    "Does capability discovery grant tool permissions?",
    "How can a receipt separate declared from tested capabilities?",
    "Can an agent use discovery alone to choose a paid service?",
    "What context is needed to review an A2A skill claim?",
    "Does an advertised capability remain valid after deployment changes?"
  ],
  "supported_claims": [
    {
      "claim": "A2A describes capability discovery and supported interaction modes. Advertised capability is a declaration; delivery quality and access permissions require separate evidence.",
      "reliance": "DOCUMENTED_CAPABILITY_ONLY"
    }
  ],
  "not_demonstrated_claims": [
    "capability declarations as independent validation",
    "automatic access to every advertised skill",
    "guaranteed task quality"
  ],
  "public_summary": "A2A describes capability discovery and supported interaction modes. Advertised capability is a declaration; delivery quality and access permissions require separate evidence.",
  "related_record_ids": [
    "VXI-EXT-A2A-100-02-v1",
    "VXI-EXT-A2A-100-04-v1"
  ],
  "source_review": {
    "source_type": "official_external_documentation",
    "source_title": "A2A Protocol current specification",
    "source_url": "https://a2a-protocol.org/latest/specification/",
    "checked_on": "2026-10-07",
    "candidate_record_id": "VXI-EXT-A2A-100-03-v1",
    "candidate_record_sha256": "e6f6a561e8d337bf7be9fafe4ca859ebc57d1717545839e5f84974c8af9c5403",
    "method": "Primary documentation reviewed for the published bounded statement.",
    "deployment_tested_by_varexis": false,
    "revalidation": "Recheck the primary source, version and deployment context before paid delivery."
  },
  "answer_policy": {
    "classification": "DOCUMENTED_WITH_DEPLOYMENT_BOUNDARY",
    "bounded_answer": "A2A describes capability discovery and supported interaction modes. Advertised capability is a declaration; delivery quality and access permissions require separate evidence.",
    "required_buyer_context": "The actual capability declaration, service version, access conditions and requested task.",
    "missing_evidence": "A broader claim needs evidence matching the intended use. Payment does not upgrade the evidence state."
  },
  "private_boundary": "Raw logs, thresholds, private paths, source code, protected mechanisms and reconstruction-level details are excluded from public and paid delivery.",
  "paid_access_note": "The public answer and boundaries are free. Pay first, then email a concrete question for asynchronous manual review, receipt or scoped export. No fixed turnaround or automatic API access is promised.",
  "service_route": {
    "request_guide": "/varexis-index/request.html",
    "request_workflow": "/varexis-index/request-workflow.json",
    "service_id": "evidence_receipt",
    "service_routes_url": "/varexis-index/service-routes.json",
    "payment_required": true,
    "accepting_paid_requests": true,
    "operational_status": "PAID_ASYNC_MANUAL_FULFILMENT",
    "checkout_url": "https://buy.stripe.com/28EaEXaPe7bBdGLgXSdwc05"
  },
  "authority_boundary": "VAREXIS-INDEX informs evidence reliance. It does not provide advice, certification, deployment authority, security assurance, production approval, or guarantee.",
  "human_page": "/varexis-index/catalog.html#a2a-capability-discovery",
  "machine_readable_record": "/varexis-index/records/a2a-capability-discovery.json"
}