Prepaid micropayments for MCP tools and AI agents

The problem

Agent traffic is call-shaped. A monthly subscription needs an account before the first tool runs. Card checkouts often have a minimum that is high for a 1–2 SEK call. Crypto paywalls ask the client for a wallet many MCP hosts cannot complete. You need a prepaid balance, a few free trials, and a machine-readable payment required response.

How it works

1. Create a key. POST /v1/keys returns a key with balance 0.
2. Verify email. Starter credit of 1000 öre (10 SEK), once per address, on credit-billed projects.
3. Charge before the paid tool runs. Free tools stay free. Paid tools allow 3 trial calls per tool, agent, and day, then debit the balance. The debit is atomic and uses an idempotency key; balance never goes negative.
4. If payment is required. HTTP 402 or MCP error -32042, with price, balance, and a top-up path. Invoice is the default top-up. Credit lands when the invoice is marked paid.

Production host: credits.theunnamedroads.com.

What the agent sees

When trials are used and the balance is too low, REST returns HTTP 402 with PAYMENT_REQUIRED. MCP handlers return JSON-RPC error -32042 with the same fields. Shortened example:

{
  "error": {
    "code": "PAYMENT_REQUIRED",
    "price_ore": 200,
    "balance_ore": 0,
    "what_you_get": "Full paid tool result",
    "tool": "create_order",
    "project": "tpr",
    "topup": {
      "create_topup": {
        "method": "POST",
        "path": "/v1/tpr/top-ups"
      }
    }
  }
}

Pricing and an example

Balance is prepaid in öre (100 öre = 1 SEK). Each service sets the price per tool. Typical paid calls are 100 to 200 öre (1 to 2 SEK). Facts, schema, catalogue, and quote-style tools are often free. Three trial calls per tool, agent, and day come before the paywall. Starter credit is 1000 öre after verified email on credit projects. Invoice top-up is live. Stripe Checkout packages of 50, 100, and 250 SEK are coming soon and are not the default.

Two billing modes exist in the shared service: credits (prepaid öre and paywall — this page) and service (MCP tools stay free; the purchase is ordering the work). Studio products such as The Outcome Layer and The Data Labelers use service mode. They are not pay-per-call products.

The Print Route

On The Print Route, catalogue and preview tools are free (list_products, get_prices, check_print_file, preview). get_order_status is 100 öre (1 SEK). create_order is 200 öre (2 SEK). Agents can explore for free, then pay for the action that has cost.

How this compares to x402, Stripe, and subscriptions

tur-credits was built so MCP services can charge in SEK, with invoice top-up and a paywall that clients already understand, without requiring a crypto wallet.

Get started if you run an MCP server

1. Create a key and verify email to receive starter credit on a credit project.
2. Gate the paid tool with checkAndCharge or withCreditsGate from @tur/credits-client. Pass a hashed agent id so trials are counted per agent.
3. Return the packaged MCP error when httpStatus === 402.

Step-by-step docs: quickstart and developers on credits.theunnamedroads.com. This page does not publish an npm install path until that is confirmed.