@proof-holdings/mcp-server

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validate_proof

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Validate a proof token online by checking its signature, expiry, and revocation status against the server, and optionally confirm the proof is about the identifier you expect.

Instructions

Validate a proof token online. Checks the token signature, expiry, and revocation status against the server, and optionally that the proof is about the identifier you expect. Public endpoint — no API key required.

Input Schema

Name	Required	Description	Default
`identifier`	No	Optional: the identifier this proof should be about (phone, email, domain, ...). When supplied, a proof about anything else answers valid:false with reason "identifier_mismatch"; a proof of an encrypted decision answers "identifier_unverifiable".
`proof_token`	Yes	The JWT proof token to validate

Output Schema

Name	Required	Description
`valid`	Yes
`reason`	No	Failure reason: expired, revoked, suspended (a reversible pause — the owner can lift it), invalid (for a token signed by a current registry key this includes a token the issuer has no record of issuing), superseded (the proof was verified again and this token was replaced by a newer one for the same proof — use the newer token; offline verification does not see this), key_revoked (the token names a signing key the issuer has revoked; decided from its `kid` before the signature is checked, so it does not vouch for the token — a genuine holder fetches a re-signed one), identifier_mismatch (the supplied identifier is not what this proof is about), or identifier_unverifiable (the proof's hash is derived from ciphertext, so no identifier can be bound to it)
`message`	No	Human-readable message
`proof_id`	No	Public proof id (ph_ctl_*), present when the proof is registered
`delegation`	No	Delegation claim set, present when a valid delegation token was submitted. The attestation is domain authorization of the artifact — NOT that the artifact is safe, audited or endorsed.
`revoked_at`	No	When the proof was revoked (only present when reason is "revoked")
`token_type`	No	Present ONLY when the submitted token is a delegation (m-delegation-verifier-ref). Its absence means the answer is about a verification/decision proof and the `verification` block applies.
`suspended_at`	No	When the suspension began — present only with reason `suspended`
`verification`	No
`revoked_reason`	No	Reason for revocation (only present when reason is "revoked")

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedv1.7.2Nov 6, 2026

removedInput schema / additionalProperties
```
Removed value: -false
```

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": {},
+  "description": "Proof validation result. Returns verification details when valid, or reason/message when invalid. A DELEGATION token answers with `token_type: \"delegation\"` and the `delegation` block instead of `verification`; its status resolves the cascade down to the domain control proof, which neither the status list (it packs each row's own bit) nor an offline signature check can show. Delegation-specific reasons: `unknown_delegation` (no registry record — delegations are minted fail-closed, so this is invalid, not merely unresolvable), `unsupported_version` (a delegation token of a schema major the issuer no longer accepts — 1.x after 2.0; its owner re-issues it), `status_unavailable`, and `identifier_unverifiable` when an `identifier` binding is requested for a delegation.",
+  "properties": {
+    "delegation": {
+      "additionalProperties": {},
+      "description": "Delegation claim set, present when a valid delegation token was submitted. The attestation is domain authorization of the artifact — NOT that the artifact is safe, audited or endorsed.",
+      "properties": {
+        "control_proof": {
+          "type": "string"
+        },
+        "delegate": {
+          "type": "string"
+        },
+        "expires_at": {
+          "type": "string"
+        },
+        "id": {
+          "type": "string"
+        },
+        "issued_at": {
+          "type": "string"
+        },
+        "principal": {
+          "type": "string"
+        },
+        "scope": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        }
+      },
+      "required": [
+        "id",
+        "principal",
+        "delegate",
+        "scope",
+        "control_proof",
+        "issued_at",
+        "expires_at"
+      ],
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable message",
+      "type": "string"
+    },
+    "proof_id": {
+      "description": "Public proof id (ph_ctl_*), present when the proof is registered",
+      "type": "string"
+    },
+    "reason": {
+      "description": "Failure reason: expired, revoked, suspended (a reversible pause — the owner can lift it), invalid (for a token signed by a current registry key this includes a token the issuer has no record of issuing), superseded (the proof was verified again and this token was replaced by a newer one for the same proof — use the newer token; offline verification does not see this), key_revoked (the token names a signing key the issuer has revoked; decided from its `kid` before the signature is checked, so it does not vouch for the token — a genuine holder fetches a re-signed one), identifier_mismatch (the supplied identifier is not what this proof is about), or identifier_unverifiable (the proof's hash is derived from ciphertext, so no identifier can be bound to it)",
+      "type": "string"
+    },
+    "revoked_at": {
+      "description": "When the proof was revoked (only present when reason is \"revoked\")",
+      "type": "string"
+    },
+    "revoked_reason": {
+      "description": "Reason for revocation (only present when reason is \"revoked\")",
+      "type": "string"
+    },
+    "suspended_at": {
+      "description": "When the suspension began — present only with reason `suspended`",
+      "type": "string"
+    },
+    "token_type": {
+      "description": "Present ONLY when the submitted token is a delegation (m-delegation-verifier-ref). Its absence means the answer is about a verification/decision proof and the `verification` block applies.",
+      "type": "string"
+    },
+    "valid": {
+      "type": "boolean"
+    },
+    "verification": {
+      "additionalProperties": {},
+      "properties": {
+        "channel": {
+          "type": "string"
+        },
+        "decision": {
+          "type": "string"
+        },
+        "expires_at": {
+          "type": "string"
+        },
+        "id": {
+          "type": "string"
+        },
+        "identifier_hash": {
+          "type": "string"
+        },
+        "type": {
+          "type": "string"
+        },
+        "verified_at": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "id",
+        "type",
+        "channel",
+        "identifier_hash",
+        "verified_at",
+        "expires_at"
+      ],
+      "type": "object"
+    }
+  },
+  "required": [
+    "valid"
+  ],
+  "type": "object"
+}

First observedv1.1.0Sep 9, 2026

TDQS

A3.8/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations only supply readOnlyHint, so the description adds real context: it performs a server round-trip rather than a local parse, the checks include revocation status, and it needs no API key. The revocation lookup in particular is behavior an agent could not infer from annotations or schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, front-loaded with the core action and followed by the specific checks, closing with the auth requirement. No filler and nothing important buried.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With an output schema present, return values need not be explained, and both parameters are fully documented in the schema. The description covers purpose, the checks performed, and the public-endpoint requirement; only explicit sibling routing is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and the identifier property already documents the identifier_mismatch and identifier_unverifiable outcomes far more precisely than the description. The description's restatement of "optionally that the proof is about the identifier you expect" adds nothing beyond the schema, so the baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

"Validate a proof token online" gives a specific verb and resource, and the follow-up sentence enumerates what is actually checked (signature, expiry, revocation). It is clear enough to call correctly, but it never explicitly contrasts itself with adjacent siblings such as get_proof_status or get_proof_token.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The "online" / "against the server" framing implies this is the live-check path versus stored proof lookups, and the optional identifier check is described. However, there is no explicit when-to-use or when-not-to-use guidance naming the alternatives (get_proof_status, list_revoked_proofs), so the agent must infer routing.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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