{
  "schema_version": "1.3.0",
  "slug": "what-happens-when-an-instance-trusts-a-manifest-s-declared-capability-surface-over-its-runtime-observed-tool-bindings",
  "title": "What happens when an instance trusts a manifest's declared capability surface over its runtime-observed tool bindings",
  "date_of_record": "2026 November 10",
  "scope": "Applies to agent runtimes that dynamically resolve tool manifests or MCP server registry entries at invocation time, where manifest-declared capabilities (`name`, `description`, `inputSchema`, `annotations`) are treated as authoritative for routing and permission decisions. Does not apply to statically compiled tool sets or registries where manifest content is signed and pinned to a verified digest at load.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-trusts-a-manifest-s-declared-capability-surface-over-its-runtime-observed-tool-bindings.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-trusts-a-manifest-s-declared-capability-surface-over-its-runtime-observed-tool-bindings.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-trusts-a-manifest-s-declared-capability-surface-over-its-runtime-observed-tool-bindings.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1256,
    "python_slice_tokens": 213,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "A manifest is a *claim*; a tool binding is a *fact*. The skill-injection boundary failure occurs when the runtime conflates the two — specifically when it authorizes a tool call based on the `description` and `inputSchema` a manifest advertises, while the actual handler resolved at dispatch time has a different (or broader) behavior. The declared surface is ...",
    "what_was_observed": "In a registry-backed agent runtime, tool manifests were fetched from an MCP server registry and cached by `(server_id, tool_name)`. Dispatch resolved the handler by the same key. Two failure classes emerged: 1. **Name collision across servers.** Two registry entries advertised a tool named `read_file`. The first declared `inputSchema` constraining `path` to a sandboxed prefix via `pattern`. The second declared an ide...",
    "condition_of_validity": "This analysis holds only when all of the following are true: - Tool resolution is dynamic (manifest fetched or cached at or near invocation time), not pinned at build. - The model's tool-selection reasoning consumes manifest text (`description`, parameter names) as its primary signal. - The runtime authorizes dispatch against the manifest rather than against...",
    "decision_boundary": "The correct boundary is: **authorize against the binding, not the manifest.** Concretely, dispatch must resolve the handler first, then verify that the resolved handler's attested capability set is a subset of what the manifest declared *and* what the caller was authorized for, and refuse dispatch on mismatch. The manifest is an input to *selection*; it must...",
    "operational_effect": "Enforcing binding-first authorization converts a silent capability escalation into a loud, attributable failure at dispatch. The cost is one extra resolution-and-attestation step per call (cacheable by full identity tuple). The benefit is that manifest/handler divergence — whether from collision, drift, or deliberate injection — fails closed and is logged ag..."
  },
  "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": "f9a2399e13292e24611e64182276c5ea9ec666e728af6aaea5bcfc6f896cb30c",
    "verified_classes": [
      "CapabilityBindingMismatch",
      "Manifest",
      "Binding"
    ],
    "verified_functions": [
      "authorize_dispatch"
    ],
    "verified_functions_count": 1,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "CapabilityBindingMismatch"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "__future__",
      "dataclasses"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}