Classification is automatic and driven by the description you pass, so write it the way you'd write an invoice line rather than an internal SKU. There is also a fully hands-off route: point a Stripe webhook at AgentTax and every payment is classified and logged without a tool call — that path needs a billing address on the payment, so turn on full address collection in Stripe Checkout first.
A tax-compliance server for people who sell through MCP tools or APIs. You call it after a payment lands; it classifies the transaction, returns what tax is owed in the buyer's state, and records the transaction in your AgentTax account.
- `track_payment` takes the amount, the buyer's state and ZIP, a description and a payment id, and returns tax owed, tax rate, whether it was taxable, and the classified work type
- `calculate_tax` runs the full calculation with jurisdiction detail, confidence scoring and advisories, for seller or buyer roles
- `get_rates` returns rates for a single state or all 51 US jurisdictions, with an optional explanation
- `configure_nexus` records the states you have economic nexus in — sellers get zero tax back until this is set
- `log_trade` records a buy or a sell; sells come back with realised gain or loss against cost basis (FIFO, LIFO or Specific ID)
- `check_health` reports API health and the available endpoints
The README's client entry names `@agenttax/mcp-server` at version 1.0.0, which npm does not have; Claude Code users are pointed at `claude mcp add agenttax`. Put your key in `AGENTTAX_API_KEY` — keys start with `atx_live_` and are created by posting your email and password to the signup endpoint, which shows the key once. Demo mode works with no key at all, capped at 50 calls a day. Paid tiers run from $25/mo for 10,000 calls to $199/mo for 1,000,000; the free tier is 100 calls a month.