# tollbooth-x402

Free **MCP server** for [x402toll.com](https://x402toll.com) — a toll plaza of **verified,
pay-per-call calculators for AI agents**. Discover the catalog, run free coarse previews, verify any
paid response's provenance hash, and learn how to pay. The paid endpoints charge a few cents of USDC
per call over the **x402** protocol on Base — no account, no API key.

Why agents pay: the answers depend on exact **2026** data (tax brackets, contribution limits, state
fees) a model can't reliably know, every answer is checked against hand-verified reference values,
and each ships with a formula trace and a reproducible SHA-256 hash.

## Install

```bash
npx -y tollbooth-x402
```

Add to an MCP client (e.g. Claude Desktop / Cursor):

```json
{
  "mcpServers": {
    "tollbooth": { "command": "npx", "args": ["-y", "tollbooth-x402"] }
  }
}
```

## Tools (all free, no wallet)

- **`tollbooth_catalog`** — every endpoint with prices, input schemas, methods, and golden-vector evidence.
- **`tollbooth_preview`** — a free rounded preview of a tool (paycheck, self-employment tax, capital gains, mortgage affordability, LLC cost, debt plan, impermanent loss).
- **`tollbooth_verify_hash`** — re-derive a paid response's hash to confirm it wasn't altered.
- **`tollbooth_how_to_pay`** — the x402 payment flow for the paid endpoints.

Paid calls are made directly against `https://x402toll.com` by an x402-capable wallet/client. Set
`TOLLBOOTH_URL` to point at a different gateway.

## Categories

Tax & payroll · Crypto & DeFi · Lending · Real estate · Retirement · Business.

MIT licensed. Estimates only — not financial, legal, or tax advice.