ToolVet
80trust / 100

Changed

by Forest Agent Tools in Onchain & crypto

x402 APIPassing, checked 2 h ago

Auto-detect a public MCP endpoint era, fingerprint its complete normalized tools/list schema contract and optionally compare it with a caller-provided previous SHA-256 hash. Cosmetic descriptions are excluded so text-only edits do not trigger contract drift. Base mainnet USDC

POST https://http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run/mcp/changed

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Uptime
100%
Response time
124 ms typical, 269 ms slowest 5%
Last check
2 h ago
Next check
any minute now

How to call it

POST https://http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run/mcp/changed

Each call costs $0.004 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://http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run/mcp/changed
content-type: application/json

{
  "previous_hash": "0000000000000000000000000000000000000000000000000000000000000000",
  "url": "https://http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run/fixtures/mcp"
}

Parameters

ParameterTypeRequiredDescription
previous_hashstring or nullNoEarlier result hash used to detect a material change.
protocol_versionstringNoPublic protocol version value used to scope this lookup.
urlstringYesPublic HTTP(S) URL to inspect, resolve, or compare.

Example response

The provider's example. We can't check it without paying.

Example response, 26 lines
{
  "capability": "mcp.changed",
  "data": {
    "auth_required": false,
    "changed": false,
    "new_hash": "0000000000000000000000000000000000000000000000000000000000000000",
    "previous_hash": "0000000000000000000000000000000000000000000000000000000000000000",
    "protocol_era": "modern",
    "protocol_version": "example",
    "reachable": false,
    "schema_valid": false,
    "scope": "mcp_tools_schema_contract_change_only",
    "tool_count": 0,
    "transport": "http-jsonrpc",
    "url": "example",
    "warnings": []
  },
  "meta": {
    "cache": "miss",
    "checked_at": "2026-01-01T00:00:00.000Z",
    "duration_ms": 0,
    "provider": "mcp-contract"
  },
  "ok": true,
  "version": "1"
}

Call it from code

The curl command shows the payment challenge. The JavaScript and Python versions pay and call, and never pay more than $0.004.

curl: see the payment challenge
# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run/mcp/changed' \
  -H 'content-type: application/json' \
  --data-raw '{"previous_hash":"0000000000000000000000000000000000000000000000000000000000000000","url":"https://http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run/fixtures/mcp"}'

# 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://http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run/mcp/changed' \
  -H 'content-type: application/json' \
  --data-raw '{"previous_hash":"0000000000000000000000000000000000000000000000000000000000000000","url":"https://http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run/fixtures/mcp"}' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode
JavaScript: 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 $0.004 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.004" });
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 $0.004 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fhttp--forest-gas-station-mainnet--lcjl27p8lmjs.code.run%2Fmcp%2Fchanged&method=POST
const res = await pay("https://http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run/mcp/changed", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "previous_hash": "0000000000000000000000000000000000000000000000000000000000000000",
    "url": "https://http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run/fixtures/mcp"
  }),
});
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 $0.004 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.004"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.post(
        "https://http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run/mcp/changed",
        json={
            "previous_hash": "0000000000000000000000000000000000000000000000000000000000000000",
            "url": "https://http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run/fixtures/mcp",
        },
    )
    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

WhenResultHTTPTimePrice
2 h agoPassed402116 ms$0.004
6 h agoPassed40242 ms$0.004
10 h agoPassed402295 ms$0.004
14 h agoPassed402147 ms$0.004
18 h agoPassed402132 ms$0.004
22 h agoPassed402190 ms$0.004
25 h agoPassed40236 ms$0.004
29 h agoPassed402134 ms$0.004
33 h agoPassed40241 ms$0.004
36 h agoPassed40241 ms$0.004
40 h agoPassed402180 ms$0.004
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2 days agoPassed402187 ms$0.004
2 days agoPassed402118 ms$0.004