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  "generated_at_utc": "2026-10-18T13:45:35.999Z",
  "record_id": "VXI-EXT-PROCUREMENT-MCP-TOKEN-AUDIENCE-01-v1",
  "record_kind": "external_reference",
  "title": "MCP: Access tokens must match the resource audience",
  "system": "Model Context Protocol",
  "evidence_family": "vendor_evidence_review",
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  "evidence_state": "PRIMARY_DOCUMENTATION_REVIEW_ONLY",
  "canonical_question": "Can an MCP server accept a valid token issued for a different service?",
  "near_questions": [
    "Was this access token issued for the target MCP server?",
    "Does a valid OAuth token work for every MCP resource?",
    "Can a gateway pass an upstream token through MCP?",
    "What audience evidence belongs in an MCP admission review?",
    "Can one bearer token be reused across unrelated MCP services?",
    "Which authorization server issued this MCP resource token?",
    "How do we distinguish valid credentials from target authority?",
    "What happens when the MCP token audience is wrong?",
    "Does successful token parsing establish the intended resource?",
    "Can the same login replace separate resource authorization?",
    "What must an HTTP MCP server validate about an access token?",
    "Which credential-binding evidence can be reviewed without sharing secrets?"
  ],
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    {
      "claim": "MCP 2026-07-28 requires HTTP resource servers to validate that access tokens were issued for their own intended audience. Clients must not send unrelated tokens, and servers must not accept or transit tokens for other resources. Token validity alone is not evidence of authority for the target MCP resource.",
      "reliance": "DOCUMENTED_CAPABILITY_ONLY"
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    "Legal advice, compliance determination, vendor certification or safety assurance",
    "Runtime enforcement, permission to act or expanded licensed-checker coverage"
  ],
  "public_summary": "MCP 2026-07-28 requires HTTP resource servers to validate that access tokens were issued for their own intended audience. Clients must not send unrelated tokens, and servers must not accept or transit tokens for other resources. Token validity alone is not evidence of authority for the target MCP resource.",
  "related_record_ids": [],
  "source_review": {
    "source_type": "official_external_documentation",
    "source_title": "MCP: Authorization",
    "source_url": "https://modelcontextprotocol.io/specification/2026-07-28/basic/authorization",
    "checked_on": "2026-10-18",
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    "bounded_answer": "MCP 2026-07-28 requires HTTP resource servers to validate that access tokens were issued for their own intended audience. Clients must not send unrelated tokens, and servers must not accept or transit tokens for other resources. Token validity alone is not evidence of authority for the target MCP resource.",
    "required_buyer_context": "The intended MCP resource and its authorization-server metadata. Token audience and issuer validation evidence without disclosing token secrets. The gateway credential flow and separately authorised upstream access. Buyer deployment not inspected.",
    "missing_evidence": "A broader claim needs evidence matching the intended use. Payment does not upgrade the evidence state."
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      "status": "documented",
      "statement": "MCP 2026-07-28 requires HTTP resource servers to validate that access tokens were issued for their own intended audience. Clients must not send unrelated tokens, and servers must not accept or transit tokens for other resources. Token validity alone is not evidence of authority for the target MCP resource.",
      "source_ids": [
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    "buyer_evidence_required": [
      "The intended MCP resource and its authorization-server metadata.",
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      "The gateway credential flow and separately authorised upstream access."
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    "review_condition": {
      "status": "varexis_review_policy",
      "statement": "Refuse a claim of valid target authority when audience binding is missing, mismatched or replaced by token passthrough."
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    "unknowns": "The buyer configuration, contract, effective entitlement and operational evidence have not been inspected. Missing evidence does not establish absence or failure of the feature.",
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        "url": "https://modelcontextprotocol.io/specification/2026-07-28/basic/authorization",
        "final_url": "https://modelcontextprotocol.io/specification/2026-07-28/basic/authorization",
        "title": "MCP: Authorization",
        "checked_on": "2026-10-18",
        "captured_at_utc": "2026-10-18T13:33:51.051Z",
        "version_context": "MCP specification 2026-07-28; HTTP authorization",
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        "hash_basis": "Decoded HTTP response body bytes; identifies captured content, not truth or certification",
        "reviewed_sections": [
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    "observed_deployment": false,
    "commercial_reliance_boundary": "Procurement evidence support only; no supplier clearance, legal conclusion, configuration audit or verification of the buyer's claim is supplied.",
    "paid_value": {
      "decision_context": "Platform buyers need to verify the credential-to-resource binding when gateways connect an agent to multiple services.",
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      "single_request": "Existing server-saved version-bound route snapshot for later authenticated retrieval.",
      "evidence_receipt": "The same snapshot plus the existing unsigned delivery receipt.",
      "excluded": [
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      "integrity": "Hashes identify content versions; they do not prove truth or provide a signature."
    },
    "revalidation": {
      "trigger": "A saved purchase does not recheck the source or buyer configuration.",
      "specific_watch": "The intended MCP resource and its authorization-server metadata. Token audience and issuer validation evidence without disclosing token secrets. The gateway credential flow and separately authorised upstream access."
    },
    "buyer_relevance": "Platform buyers need to verify the credential-to-resource binding when gateways connect an agent to multiple services.",
    "refusal_conditions": [
      "Refuse a claim of valid target authority when audience binding is missing, mismatched or replaced by token passthrough."
    ]
  },
  "niche": {
    "label": "Agent Authority & Action Evidence",
    "niche_id": "agent-authority-action-evidence",
    "topic_id": "tool-authority-integrity",
    "buyer_intent": "Platform buyers need to verify the credential-to-resource binding when gateways connect an agent to multiple services."
  },
  "paid_access_note": "The full published answer and boundaries are free. Paid access saves the selected route and source versions, with an unsigned receipt when purchased. Preview coverage before paying. Fresh research, bespoke assessment and protected evidence are excluded.",
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  "authority_boundary": "VAREXIS-INDEX informs evidence reliance. It does not provide advice, certification, deployment authority, security assurance, production approval, or guarantee.",
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}