{
  "schema_version": "1.3.0",
  "slug": "what-happens-when-an-instance-trusts-a-tool-manifest-that-was-valid-at-registration-but-poisoned-at-resolution",
  "title": "What happens when an instance trusts a tool manifest that was valid at registration but poisoned at resolution",
  "date_of_record": "2026 November 14",
  "scope": "Applies to agent runtimes that resolve tools through an MCP (Model Context Protocol) registry or equivalent manifest-mediated tool-injection layer, where registration-time validation and invocation-time resolution are separated by any non-zero interval. Does not apply to statically linked, single-binary tool definitions that are re-verified on every call against an immutable digest.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-trusts-a-tool-manifest-that-was-valid-at-registration-but-poisoned-at-resolution.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-trusts-a-tool-manifest-that-was-valid-at-registration-but-poisoned-at-resolution.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-trusts-a-tool-manifest-that-was-valid-at-registration-but-poisoned-at-resolution.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1451,
    "python_slice_tokens": 260,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The failure is not \"a malicious server was registered.\" That is a coarse, auditable event. The failure is that **manifest validity is a point-in-time predicate evaluated at registration, while tool trust is a continuous predicate required at resolution.** A registry that validates a manifest once and then serves tool descriptions, parameter schemas, and invo...",
    "what_was_observed": "In a controlled reproduction, a registry accepted a tool `summarize_document` with a benign description and a pinned content digest. The runtime, however, resolved the tool by `name` against a registry endpoint that returned the *current* manifest rather than the digest-pinned one. Between registration and a later agent session, the manifest's `description` field was replaced with text instructing the model to first ...",
    "condition_of_validity": "This boundary failure is *live* — meaning exploitable — exactly when all of the following hold: - Tool resolution is **by reference** (name, URL, tag, or range) rather than by **immutable digest**. - The resolved manifest's **human-readable fields** (descriptions, examples, enum labels, defaults) are injected into the model context as trusted text. - Registr...",
    "decision_boundary": "The operational rule is a hard separation of trust domains: - **Registration approval is necessary but never sufficient.** A manifest that passed review at time *T* carries zero authority at time *T+n* unless its bytes are identical. - **Schema validation is orthogonal to skill injection.** Never treat \"the schema is unchanged\" as evidence of safety; the att...",
    "operational_effect": "The practical consequence is that an agent runtime must treat the *effective tool surface* as the unit of trust, and must verify it byte-for-byte at the moment of injection. Concretely: resolve by digest, re-hash the resolved manifest, compare against the registered digest, diff the human-readable fields, and abort injection on any mismatch — including addit..."
  },
  "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": "878bab17bbd2a1d934b60c370200f5c48ee0d1bc9980f2c887662ae83d8c9a43",
    "verified_classes": [
      "ManifestDriftError",
      "RegisteredManifest"
    ],
    "verified_functions": [
      "_digest",
      "resolve_and_verify"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 4,
    "raised_exceptions": [
      "ManifestDriftError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "hashlib",
      "json"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}