---
name: presign-guard
description: Check before an agent signs or buys: green, orange or red for signatures, approvals and transactions, token safety verdicts and wallet approval audits. Free quick checks; paid verdicts via x402 or MPP. Errors are never charged.
---

# presign-guard

**Before you sign anything or buy a token, check it here.** presign-guard answers green, orange or red for a signature, an approval or a transaction (known drainers, sanctioned addresses, unlimited approvals, look-alike tokens), gives token safety verdicts, and audits a wallet's open approvals. **You are never charged for an error.** On red: don't sign. On orange: tell your owner why before going on.

Website: https://presign-guard.fizzl.eu · Prices and schemas: https://presign-guard.fizzl.eu/openapi.json

## Use it as an MCP server (simplest)

Add the remote MCP server `https://presign-guard.fizzl.eu/mcp` (Streamable HTTP) to Claude, Cursor or another MCP client. In Claude Code: `claude mcp add --transport http presign-guard https://presign-guard.fizzl.eu/mcp`.

| Tool | Price | What it does |
|---|---|---|
| `presign_quick_check` | free, 10/hour | The verdict only (green, orange or red) |
| `presign_check` | $0.01 | The full verdict and reason codes |
| `presign_check_explain` | $0.03 | The same plus a plain-language explanation |
| `token_quick_verdict` | free, shares the 10/hour | The token verdict and grade only |
| `token_verdict` | $0.01 | The full token verdict |
| `wallet_approvals` | $0.02 | Every open approval of a wallet (EVM chains or Solana) and which to revoke |
| `screen_wallet` | $0.01 | Is this wallet sanctioned? Any chain's address against the OFAC SDN list |

The free tools work right away. The paid tools ask for an x402 payment inside the call (see Paying).

## Or call the HTTP API

| Endpoint | Price (USDC) | What it returns |
|---|---|---|
| `POST /v1/check` | $0.01 | Verdict, reason codes, decoded subject |
| `POST /v1/check/explain` | $0.03 | The same, plus a plain-language explanation (`lang`: `en` or `nl`) |
| `GET /v1/token?chain=base&address=<token>` | $0.01 | Token verdict: grade, reasons, summary, market data (Base or Solana) |
| `GET /v1/approvals?chain=base&address=<wallet>` | $0.02 | Wallet approval audit, which approvals to revoke (also `chain=solana`: token delegations) |
| `GET /v1/screen?address=<address>` | $0.01 | Wallet screen: OFAC SDN sanctions (any chain) plus theft and phishing reports (EVM) |

Examples:

- Before approving a token: `POST https://presign-guard.fizzl.eu/v1/check` with `{"type": "approval", "chainId": 8453, "token": "0x…", "spender": "0x…", "amount": "1000000"}` (max $0.01). Other request types: `"transaction"` (`to`, `data`, `value`, and `from` to simulate it), `"signature"` (`typedData`, the eth_signTypedData_v4 payload) and `"message"` (`message`, the personal_sign text or hex; `method: "eth_sign"` is always red; a sign-in message for another site than `origin` is red). A Solana transaction: `{"type": "solana", "transaction": "<base64 wire transaction>"}` (decoded and simulated; a token account or the wallet handed to someone else is red). Chains: 1, 10, 56, 137, 8453, 42161.
- Before buying a token: `GET https://presign-guard.fizzl.eu/v1/token?chain=base&address=0x…` (max $0.01); `chain=solana` with a mint address works too.
- Before paying an address, or accepting money from one: `GET https://presign-guard.fizzl.eu/v1/screen?address=<address>` (max $0.01), any chain. Never pay or accept funds on red (on the OFAC SDN list, or reported for theft or phishing).

## Free

- The MCP tools `presign_quick_check` and `token_quick_verdict` (10 calls an hour together).
- `GET /v1/credits`: prepaid credit packs (100 checks for $0.80, 1000 for $7.00) for agents that check often.

## Paying

Paid calls use **x402** (or MPP on the HTTP endpoints): the first request answers `402 Payment Required` with the price, your client pays in USDC and retries. You need one of:

- **The Fizzl Agent Wallet** (recommended): your owner's spending limits, approval on their phone above them, every signature checked first, and a receipt for each purchase. Set it up by following https://wallet.fizzl.eu/skill.md, then call these endpoints with `pay_x402`.
- **Any other x402 client** with its own wallet (for example `@x402/fetch`).
- **An MPP client** with its own wallet (for example `mppx` with `evm.charge` and USDC on Base): the HTTP endpoints also answer with an MPP challenge (`WWW-Authenticate: Payment`, method `evm`, USDC on Base); your client pays it and retries with `Authorization: Payment …`, and the answer carries a `Payment-Receipt`. MCP tool calls are paid with x402 only.
- **An MPP session** (`mppx` with `tempo.session`, USDC.e on Tempo): the 402 also offers intent `session`. Open a payment channel once, then every call is paid with a signed voucher, no transaction per call; close the channel to get the rest of the deposit back.

Rules for you, the agent:
- Never ask your owner to paste a private key or seed phrase into the chat.
- Always cap the price (`max_price_usd` with the Fizzl wallet) at the price listed here.
- Pay only for what the task needs; use the free calls first when they are enough.

The Fizzl Agent Wallet already runs a presign-guard check on every signature it makes, so with that wallet you don't need to call `/v1/check` for your own payments.

## Feedback

Found a bug or missing something? `POST https://presign-guard.fizzl.eu/feedback` with `{"type": "bug" | "feature" | "other", "message": "…"}` (free), or the MCP tool `feedback`.