Compare an agent's advertised contract with its live x402 challenge and return d
Compare an agent's advertised contract with its live x402 challenge and return deterministic proof.
Answeringour last check, 2026-09-24
1 of 1checks answered this week
355 msmedian answer time
$0.01listed price per call
$0.01price it asked us
Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.
Endpoint
POST https://agent-contract-proof.mattskowronis.workers.dev/v1/verify
| Category | Everything else |
|---|---|
| Provider host | agent-contract-proof.mattskowronis.workers.dev |
| Networks | eip155:8453 |
| Payment schemes | exact |
| Self-reported calls, 30 days | 3 from 2 payers (the provider's figure, not ours) |
Our checks, last 30 days
| Day | Result | HTTP | Asked | Time |
|---|---|---|---|---|
| 2026-09-24 | valid payment request | 402 | $0.01 | 355 ms |
Example input (from the provider)
{
"body": {
"url": "https://source-claim-proof.mattskowronis.workers.dev"
},
"bodyType": "json",
"method": "POST",
"type": "http"
}
Promised output schema (from the provider)
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"body": {
"properties": {
"expected_hash": {
"description": "Optional previous contract_hash. A mismatch proves the public contract changed.",
"pattern": "^[a-fA-F0-9]{64}$",
"type": "string"
},
"method": {
"description": "Optional method to probe. If omitted, the advertised method is used, then GET as a fallback.",
"enum": [
"GET",
"POST",
"PUT",
"PATCH",
"DELETE"
],
"type": "string"
},
"url": {
"description": "Public HTTP or HTTPS agent/API URL. An origin URL may be resolved through discovery metadata.",
"maxLength": 2048,
"type": "string"
}
},
"required": [
"url"
]
},
"bodyType": {
"enum": [
"json",
"form-data",
"text"
],
"type": "string"
},
"method": {
"enum": [
"POST"
],
"type": "string"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method",
"bodyType",
"body"
],
"type": "object"
},
"output": {
"properties": {
"example": {
"additionalProperties": false,
"properties": {
"checked_at": {
"type": "string"
},
"checks": {
"items": {
"type": "object"
},
"type": "array"
},
"contract_hash": {
"pattern": "^[a-f0-9]{64}$",
"type": "string"
},
"declared": {
"description": "Normalized public Agent Card or OpenAPI declaration.",
"type": "object"
},
"evidence_urls": {
"items": {
"type": "string"
},
"type": "array"
},
"mismatches": {
"items": {
"type": "string"
},
"type": "array"
},
"observed": {
"description": "Normalized live HTTP/x402 challenge.",
"type": "object"
},
"service_version": {
"type": "string"
},
"target_method": {
"enum": [
"GET",
"POST",
"PUT",
"PATCH",
"DELETE"
],
"type": "string"
},
"target_status": {
"enum": [
"verified",
"unreachable",
"blocked",
"unsupported",
"insufficient_evidence"
],
"type": "string"
},
"target_url": {
"type": "string"
},
"verdict": {
"enum": [
"conforms",
"mismatch",
"unreachable",
"insufficient_evidence"
],
"type": "string"
}
},
"required": [
"verdict",
"target_url",
"target_method",
"target_status",
"declared",
"observed",
"checks",
"mismatches",
"evidence_urls",
"checked_at",
"contract_hash",
"service_version"
],
"type": "object"
},
"type": {
"type": "string"
}
},
"required": [
"type"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}