Agent Intel Agent Json Schema Guard
by SiteCheck Agent Intel & Dev in Other
Checks an agent's JSON output against a JSON Schema (draft 2020-12 keywords: type, properties, required, additionalProperties, items, enum, const, length, pattern, minimum/maximum, item counts). Returns valid yes/no, each error with its path and the value with disallowed fields removed. $ref, allOf/anyOf/oneOf, if/then and format return an error instead of passing silently.
https://api.fadeandco.workers.dev/api/agent-intel/agent-json-schema-guard- Price
- $0.001
- per call in USDC
- Uptime
- 0.0%
- last 30 days
- Response time
- -
- no timed checks yet
- Last check
- Failed
- 4 h ago, next any minute now
Reliability
Latest check failed 4 h ago: Amount "0.002" is not in atomic token units
Status and outage history · Atom feed · Watch with other listings
How to call it
POST https://api.fadeandco.workers.dev/api/agent-intel/agent-json-schema-guard
Each call costs $0.001 in USDC on Base, paid with the request over x402.
Run a free test callOne unpaid request, the way an agent sends it. You see the payment challenge it gets back. Nothing is charged.
Example request
From the listing.
POST https://api.fadeandco.workers.dev/api/agent-intel/agent-json-schema-guard
content-type: application/json
{
"schema": {
"additionalProperties": false,
"properties": {
"age": {
"minimum": 0,
"type": "integer"
},
"name": {
"maxLength": 40,
"type": "string"
}
},
"required": [
"name"
],
"type": "object"
},
"value": {
"age": 36,
"extra": "remove me",
"name": "Ada"
}
}Parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
schema | object | Yes | The JSON Schema |
value | any | Yes | The JSON value to check (any JSON) |
Example response
The provider's example. We can't check it without paying.
{
"checkedAt": "2026-10-23T09:35:20.029Z",
"errors": [],
"note": "Subset of JSON Schema 2020-12. Unsupported keywords are rejected, not ignored.",
"removedFields": [
"/extra"
],
"sanitized": {
"age": 36,
"name": "Ada"
},
"source": "https://json-schema.org/draft/2020-12",
"valid": true
}Call it from code
The curl command shows the payment challenge. The JavaScript and Python versions pay and call, and never pay more than $0.001.
curl: see the payment challenge
# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://api.fadeandco.workers.dev/api/agent-intel/agent-json-schema-guard' \
-H 'content-type: application/json' \
--data-raw '{"schema":{"additionalProperties":false,"properties":{"age":{"minimum":0,"type":"integer"},"name":{"maxLength":40,"type":"string"}},"required":["name"],"type":"object"},"value":{"age":36,"extra":"remove me","name":"Ada"}}'
# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - -X POST 'https://api.fadeandco.workers.dev/api/agent-intel/agent-json-schema-guard' \
-H 'content-type: application/json' \
--data-raw '{"schema":{"additionalProperties":false,"properties":{"age":{"minimum":0,"type":"integer"},"name":{"maxLength":40,"type":"string"}},"required":["name"],"type":"object"},"value":{"age":36,"extra":"remove me","name":"Ada"}}' \
| grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decodeJavaScript: pay and call
// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";
// Pays at most $0.001 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.001" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);
// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.001 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fapi.fadeandco.workers.dev%2Fapi%2Fagent-intel%2Fagent-json-schema-guard&method=POST
const res = await pay("https://api.fadeandco.workers.dev/api/agent-intel/agent-json-schema-guard", {
method: "POST",
headers: { "content-type": "application/json" },
body: JSON.stringify({
"schema": {
"additionalProperties": false,
"properties": {
"age": {
"minimum": 0,
"type": "integer"
},
"name": {
"maxLength": 40,
"type": "string"
}
},
"required": [
"name"
],
"type": "object"
},
"value": {
"age": 36,
"extra": "remove me",
"name": "Ada"
}
}),
});
console.log(res.status, await res.text());Python: pay and call
# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client
# Pays at most $0.001 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.001"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))
with x402_requests(client) as session:
res = session.post(
"https://api.fadeandco.workers.dev/api/agent-intel/agent-json-schema-guard",
json={
"schema": {
"additionalProperties": False,
"properties": {
"age": {
"minimum": 0,
"type": "integer",
},
"name": {
"maxLength": 40,
"type": "string",
},
},
"required": [
"name",
],
"type": "object",
},
"value": {
"age": 36,
"extra": "remove me",
"name": "Ada",
},
},
)
print(res.status_code, res.text)Security scan
No findings
We scan names, descriptions and tool definitions for hidden instructions and other prompt-injection patterns.
Recent checks
| When | Result | HTTP | Time | Price |
|---|---|---|---|---|
| 4 h ago | Amount "0.002" is not in atomic token units | 402 | 796 ms | $0.002 |
| 12 h ago | Amount "0.002" is not in atomic token units | 402 | 160 ms | $0.002 |
| 21 h ago | Amount "0.002" is not in atomic token units | 402 | 49 ms | $0.002 |
| 29 h ago | Amount "0.002" is not in atomic token units | 402 | 89 ms | $0.002 |
| 37 h ago | Amount "0.002" is not in atomic token units | 402 | 44 ms | $0.002 |
Show 10 older checks
| 45 h ago | Amount "0.002" is not in atomic token units | 402 | 1.0 s | $0.002 |
| 2 days ago | Amount "0.002" is not in atomic token units | 402 | 1.0 s | $0.002 |
| 3 days ago | Amount "0.002" is not in atomic token units | 402 | 105 ms | $0.002 |
| 3 days ago | Amount "0.002" is not in atomic token units | 402 | 1.4 s | $0.002 |
| 3 days ago | Amount "0.002" is not in atomic token units | 402 | 152 ms | $0.002 |
| 3 days ago | Amount "0.002" is not in atomic token units | 402 | 46 ms | $0.002 |
| 4 days ago | Amount "0.002" is not in atomic token units | 402 | 103 ms | $0.002 |
| 4 days ago | Amount "0.001" is not in atomic token units | 402 | 686 ms | $0.001 |
| 4 days ago | Amount "0.001" is not in atomic token units | 402 | 41 ms | $0.001 |
| 5 days ago | Amount "0.001" is not in atomic token units | 402 | 105 ms | $0.001 |