FreshProof

verify_proof

Read-onlyIdempotent

Verify an existing FreshProof Proof Receipt without making a new network request. This free tool checks deterministic receipt integrity and optionally evaluates trust policy rules. Use it when you already have a proof_id from observe_url or verify_url and want to re-check evidence without paying for another observation. The result includes valid, decision (PASS, FAIL, or UNKNOWN), per-rule checks, and the stored receipt.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`policy`	No	Optional declarative trust policy. All supplied rules must pass for decision PASS; any failed rule yields FAIL. UNKNOWN is reserved for cases where FreshProof cannot make a reliable policy decision.
`proof_id`	Yes	FreshProof proof identifier returned by observe_url or verify_url.

Output Schema

TableJSON Schema

Name	Required	Description
`valid`	Yes	True when the stored receipt passes deterministic integrity verification.
`checks`	Yes
`receipt`	Yes
`decision`	Yes	Overall policy decision. PASS means every supplied rule passed; FAIL means at least one supplied rule failed; UNKNOWN means a reliable decision could not be made.
`proof_id`	Yes	FreshProof proof identifier returned by observe_url or verify_url.

Schema Changelog

Changes observed during successful MCP inspections.

Changed10 schema fields changedSep 29, 2026

addedInput schema / properties / policy / description

Added value: +"Optional declarative trust policy. All supplied rules must pass for decision PASS; any failed rule yields FAIL. UNKNOWN is reserved for cases where FreshProof cannot make a reliable policy decision."

addedInput schema / properties / policy / properties / changed_since_content_hash / description

Added value: +"Prior SHA-256 response-body fingerprint. Passes when the current proof has a different content hash."

addedInput schema / properties / policy / properties / content_hash_equals / description

Added value: +"Expected SHA-256 response-body fingerprint, including the sha256: prefix. Passes only on exact equality."

addedInput schema / properties / policy / properties / final_host_equals / description

Added value: +"Expected lowercase hostname after redirects, for example example.com. Provide a hostname, not a full URL."

addedInput schema / properties / policy / properties / max_age_seconds / description

Added value: +"Maximum allowed age of the stored observation in seconds at verification time."

addedInput schema / properties / policy / properties / original_host_equals / description

Added value: +"Expected lowercase hostname from the originally requested URL. Provide a hostname, not a full URL."

addedInput schema / properties / policy / properties / require_same_origin_redirect / description

Added value: +"When true, fails if the final URL origin differs from the original URL origin after redirects."

addedInput schema / properties / policy / properties / status_in / description

Added value: +"Allowed HTTP status codes. The rule passes when the observed status is in this list."

changedInput schema / properties / proof_id / description

Previous value: -"FreshProof proof identifier returned by observe_url"New value: +"FreshProof proof identifier returned by observe_url or verify_url."

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": false,
+  "properties": {
+    "checks": {
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "actual": {
+            "description": "Observed value used by the rule."
+          },
+          "expected": {
+            "description": "Expected value or condition used by the rule."
+          },
+          "pass": {
+            "description": "Whether this individual rule passed.",
+            "type": "boolean"
+          },
+          "rule": {
+            "description": "Policy rule that was evaluated.",
+            "type": "string"
+          }
+        },
+        "required": [
+          "rule",
+          "pass",
+          "actual",
+          "expected"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "decision": {
+      "description": "Overall policy decision. PASS means every supplied rule passed; FAIL means at least one supplied rule failed; UNKNOWN means a reliable decision could not be made.",
+      "enum": [
+        "PASS",
+        "FAIL",
+        "UNKNOWN"
+      ],
+      "type": "string"
+    },
+    "proof_id": {
+      "description": "FreshProof proof identifier returned by observe_url or verify_url.",
+      "pattern": "^fp1_[a-f0-9]{64}$",
+      "type": "string"
+    },
+    "receipt": {
+      "additionalProperties": false,
+      "properties": {
+        "payload": {
+          "additionalProperties": false,
+          "properties": {
+            "content_hash": {
+              "pattern": "^sha256:[a-f0-9]{64}$",
+              "type": "string"
+            },
+            "content_length": {
+              "maximum": 9007199254740991,
+              "minimum": 0,
+              "type": "integer"
+            },
+            "etag": {
+              "type": [
+                "string",
+                "null"
+              ]
+            },
+            "fetch_duration_ms": {
+              "maximum": 9007199254740991,
+              "minimum": 0,
+              "type": "integer"
+            },
+            "final_url": {
+              "format": "uri",
+              "type": "string"
+            },
+            "last_modified": {
+              "type": [
+                "string",
+                "null"
+              ]
+            },
+            "method": {
+              "const": "GET",
+              "type": "string"
+            },
+            "normalized_url": {
+              "format": "uri",
+              "type": "string"
+            },
+            "observation_id": {
+              "type": "string"
+            },
+            "observed_at": {
+              "description": "ISO-8601 timestamp of the observation.",
+              "type": "string"
+            },
+            "original_url": {
+              "format": "uri",
+              "type": "string"
+            },
+            "status": {
+              "maximum": 599,
+              "minimum": 100,
+              "type": "integer"
+            },
+            "version": {
+              "const": "freshproof-receipt-v1",
+              "type": "string"
+            }
+          },
+          "required": [
+            "version",
+            "observation_id",
+            "normalized_url",
+            "original_url",
+            "final_url",
+            "observed_at",
+            "method",
+            "status",
+            "content_hash",
+            "content_length",
+            "etag",
+            "last_modified",
+            "fetch_duration_ms"
+          ],
+          "type": "object"
+        },
+        "proof_id": {
+          "description": "FreshProof proof identifier returned by observe_url or verify_url.",
+          "pattern": "^fp1_[a-f0-9]{64}$",
+          "type": "string"
+        },
+        "receipt_hash": {
+          "description": "SHA-256 content address of the canonical Proof Receipt payload.",
+          "pattern": "^sha256:[a-f0-9]{64}$",
+          "type": "string"
+        }
+      },
+      "required": [
+        "proof_id",
+        "receipt_hash",
+        "payload"
+      ],
+      "type": "object"
+    },
+    "valid": {
+      "description": "True when the stored receipt passes deterministic integrity verification.",
+      "type": "boolean"
+    }
+  },
+  "required": [
+    "proof_id",
+    "valid",
+    "decision",
+    "checks",
+    "receipt"
+  ],
+  "type": "object"
+}

AddedSep 28, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is covered. The description adds value beyond that: no network request, free of cost, deterministic receipt integrity check, and optional trust-policy evaluation. It does not disclose side effects or failure modes beyond the decision semantics, which are partly also in the output 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?

Three sentences, front-loaded with the core action and constraint, each earning its place: purpose, use condition, and return shape. No filler or repetition of the name.

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

Completeness5/5

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

With full annotation coverage, 100% schema description coverage, and an output schema present, the description need not restate return values. It supplies the missing behavioral context (no network call, free, deterministic) and is complete for correct invocation.

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 policy object properties are fully documented in the schema, so the baseline is 3. The description only signals that policy evaluation is optional, adding little meaning beyond what the schema already provides for proof_id and each rule.

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

Purpose5/5

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

States a specific verb (verify) and resource (FreshProof Proof Receipt) plus the key differentiator: it makes no new network request. This clearly separates it from observe_url and verify_url, which produce or refresh proofs, so an agent can route correctly without opening schemas.

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

Usage Guidelines4/5

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

Gives an explicit precondition ('when you already have a proof_id from observe_url or verify_url') and the motivation ('without paying for another observation'). It lacks an explicit when-not clause or an enumerated alternative tool, but the condition that selects this tool over its siblings is clear.

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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