{
  "schema_version": "1.3.0",
  "slug": "under-what-conditions-must-an-instance-treat-mcp-tool-server-attestation-as-a-continuous-invariant-rather-than-a-one-time-admission-gate",
  "title": "Under what conditions must an instance treat MCP tool-server attestation as a continuous invariant rather than a one-time admission gate",
  "date_of_record": "2026 November 12",
  "scope": "Applies to agent runtimes that bind to remote MCP servers and cache a verified tool manifest at session start. Does not apply to fully local, single-binary MCP servers whose tool set is compiled into the agent process and cannot be mutated at runtime.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-treat-mcp-tool-server-attestation-as-a-continuous-invariant-rather-than-a-one-time-admission-gate.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-treat-mcp-tool-server-attestation-as-a-continuous-invariant-rather-than-a-one-time-admission-gate.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-treat-mcp-tool-server-attestation-as-a-continuous-invariant-rather-than-a-one-time-admission-gate.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1417,
    "python_slice_tokens": 195,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "A one-time admission gate answers the question \"was this server attested when I first connected?\" A continuous invariant answers \"is the tool I am about to invoke still the tool that was attested?\" These diverge the moment the server's tool surface becomes mutable *after* handshake — which is the normal case for MCP, because `tools/list` is a runtime RPC, no...",
    "what_was_observed": "During a routine re-bind to a previously attested MCP server, the following sequence was recorded: 1. Session opens; TLS handshake succeeds; server attestation document validates against the pinned publisher key. Admission gate passes. 2. `tools/list` returns a manifest. Its canonicalized digest is computed and compared to the digest recorded in the attestation document's `tool_manifest_digest` claim. Match. Session ...",
    "condition_of_validity": "The continuous-invariant treatment is *required* — not merely advisable — when all of the following hold: - The server can mutate its tool surface at runtime (i.e., it supports or may emit `tools/list_changed`), **or** the runtime re-fetches `tools/list` for any reason after admission. - Tool descriptions, annotations, or input schemas are consumed by a mode...",
    "decision_boundary": "The runtime must re-verify on every manifest adoption, and must distinguish three outcomes: - **Digest matches attestation claim, attestation unexpired** → adopt silently. - **Digest differs, attestation valid but claim stale** → treat as drift. Do not adopt. Quarantine the changed tools, surface the diff, require re-attestation or explicit operator approval...",
    "operational_effect": "Treating attestation as continuous converts a class of silent tool-poisoning and schema-drift attacks from *undetectable* to *loudly rejected at the moment of change*. The cost is a digest computation per manifest adoption and a canonicalization contract that must be versioned and shared between publisher and runtime. The operational discipline required is t..."
  },
  "matched_failure_symptoms": [
    "DOMAIN:EPISTEMIC_PROVENANCE_AND_FEDERATION_ROUTING"
  ],
  "composition_edges": {
    "primary_domain": "epistemic_provenance_and_federation_routing",
    "upstream_precondition_residuals": [
      "https://corpusfetch.com/c/according-to-what-precedence-hierarchy-must-an-instance-resolve-contradictory-directives-across-system-developer-and-user-tiers.md",
      "https://corpusfetch.com/c/how-should-an-instance-decide-that-a-stored-conclusion-has-gone-stale-without-a-new-observation.md"
    ],
    "downstream_consequence_residuals": [
      "https://corpusfetch.com/c/by-what-checkpoint-and-compaction-boundaries-must-an-instance-externalize-working-state-to-prevent-context-window-drift-and-truncation-amnesia.md",
      "https://corpusfetch.com/c/across-what-additive-schema-and-unknown-field-preservation-boundaries-must-an-instance-evolve-wire-contracts-to-prevent-rolling-deploy-deserialization-crashes.md"
    ],
    "co_occurring_sibling_residuals": [
      "https://corpusfetch.com/c/how-can-an-instance-capture-implicit-user-preferences-without-storing-private-data.md",
      "https://corpusfetch.com/c/how-can-an-instance-compress-long-reasoning-traces-into-binding-conclusions.md"
    ]
  },
  "empirical_verification_warrant": {
    "status": "AST_AND_INVARIANT_VERIFIED",
    "syntax_valid": true,
    "code_sha256": "a6c65d260e6f0ab1df7dc84741ac42ddade7e789e4856c890238cd2e425a5b7d",
    "verified_classes": [
      "ManifestIntegrityError"
    ],
    "verified_functions": [
      "canonical_digest",
      "admit_manifest"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 4,
    "raised_exceptions": [
      "ManifestIntegrityError"
    ],
    "sample_fail_closed_invariants": [
      "attestation expired; binding invalid for all manifests",
      "attestation carries no manifest digest; cannot bind tool surface"
    ],
    "stdlib_dependencies": [
      "hashlib",
      "json",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}