tollbooth-x402 MCP Server

This MCP server provides a catalog of finance/tax calculators designed for AI agents, including discovery, free coarse previews, and verification. It supports running calculators and verifying the provenance hash of any paid response, using x402toll.com’s pay-per-call model.

🛠️ Key Features

Discover a catalog of 56 x402 pay-per-call finance/tax calculators
Run free coarse previews
Verify any paid response’s provenance hash
Explain how to pay for calculator calls
Identify calculators under x402 on Base using USDC

🚀 Use Cases

Generating finance/tax answers where results depend on exact 2026 data
Using calculators for tax brackets, contribution limits, and state fees
Ensuring agent outputs are checked against hand-verified reference values

⚡ Developer Benefits

No account and no API key required
Paid endpoints charge a few cents of USDC per call over x402 on Base
Provenance hash verification for paid responses
Calculator availability is part of a searchable catalog

⚠️ Limitations

Focused on finance/tax calculators and 2026-specific data
Paid calls are described as few cents per call, implying usage costs

tollbooth-x402

Free MCP server for 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.

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.

io.github.SolomonisBlack/tollbooth-x402