agent-payment

Invoke an upstream API service through LemonCake's pay-per-call proxy. Each successful call automatically debits USDC from your wallet via the permit you signed. LemonCake never holds your USDC — the transfer is direct wallet → provider on Base. PRECONDITIONS: • LEMON_CAKE_PERMIT env var must be set for real services. Get one in ~30 seconds at https://lemoncake.xyz/start/v2 (sign in with Google, sign 1 EIP-712 permit, copy the blob). If missing, the tool returns a structured PERMIT_MISSING error with how-to-fix steps. • DEMO MODE: any serviceId starting with `demo_` works WITHOUT a permit and hits real free upstreams (Wikipedia / httpbin / Open-Meteo / Nominatim / MyMemory / dictionaryapi / worldtimeapi / open.er-api). 8 demos cover search / echo / fx / translate / weather / geocode / time / dictionary — useful for Glama Inspector or new-user trial. They are marked with `mode: "demo"` and incur no charge. • serviceId must come from list_services. BEHAVIOR: • Returns the upstream response body verbatim (JSON or text), plus the X-Charge-Id and X-Amount-Usdc headers reported by the proxy. • HTTP 402 Payment Required is returned as a normal result (NOT thrown) so the agent can autonomously stop spending when the daily $25 permit cap is exhausted. • Pass the same idempotencyKey to retry safely without double-charging. • This tool spends real money and contacts an external service — it is non-idempotent by default and has external side effects. x402-COMPATIBLE INTERFACE: • Successful calls include an `x402Receipt` field with { scheme, chain, asset, amount, recipient, paymentIntentId, settledAt }. Same shape as on-chain x402 receipts so the agent's payment-handling logic is portable. • If upstream returns an x402 challenge (WWW-Authenticate: x402, X-402-* headers, or body.x402), it's parsed into `x402Challenge` for the agent to reason about. • If upstream returns 202 + Retry-After + X-Payment-Status: pending, the result is `{ status: "PAYMENT_PENDING", paymentIntentId, retryAfterMs, retryContract }`. Re-call with the same idempotencyKey to resume — no double-charge. Returns: { status, chargeId, amountUsdc, response, x402Receipt?, x402Challenge?, hint? }

Check the current on-chain USDC balance of the wallet that owns the configured permit. PRECONDITIONS: • DEMO MODE (no LEMON_CAKE_PERMIT): returns a canned $1.00 demo balance so trial users see something useful before signing. • LIVE: queries Base USDC.balanceOf(owner) directly + reports remaining daily permit cap. LemonCake's backend doesn't store the balance — it's read from the chain. Use BEFORE call_service to confirm sufficient funds and remaining daily cap. Returns: { balanceUsdc, dailyCap, remainingToday, ownerAddress, [mode], [note] }

Run a Japanese tax compliance check on a single transaction. No authentication required. Performs three checks in one call: 1. Validates the qualified-invoice registration number (T-number) against the NTA registry. 2. Determines whether source-withholding (源泉徴収) applies based on the service description. 3. If withholding applies, computes the withholding amount and net payable. Intended for Japanese corporations that pay AI / API services and need to file withholding correctly under the qualified-invoice (インボイス制度) regime. Returns: { invoice: { valid, name, ... }, withholding: { required, rate, amount, net } } Errors: invalid registrationNumber returns invoice.valid = false (not an exception).

Return public usage statistics for every approved service on the marketplace. No authentication required. Use this AFTER list_services and BEFORE call_service to pick a service based on real-world traction (call counts, USDC revenue, last-used timestamp). Returns: an array of { serviceId, callCount, totalRevenueUsdc, lastCalledAt }.

List approved API services available on the LemonCake marketplace. No authentication required. Use this BEFORE call_service to discover serviceId values and per-call USDC pricing. When LEMON_CAKE_PERMIT is missing, 8 demo services are prepended: demo_search → Wikipedia opensearch demo_echo → httpbin.org/anything demo_fx → live FX rates (open.er-api) demo_translate → 80+ languages (MyMemory) demo_weather → current weather any lat/lon (Open-Meteo) demo_geocode → place name → lat/lon (OpenStreetMap Nominatim) demo_time → IANA timezone time + DST (worldtimeapi) demo_dictionary → English definitions / synonyms (dictionaryapi.dev) All real upstreams, no auth, free. Live users (permit set) see real marketplace entries; demo_* IDs remain callable directly. Each item: { id, name, provider, type ('API' | 'MCP'), pricePerCall, [usage], [mode] }. Errors: HTTP-level errors are returned as `Error: API <status>: <body>`.

Show the LemonCake MCP first-run setup guide. No authentication required. Call this tool FIRST to learn what is missing and how to obtain a permit. If LEMON_CAKE_PERMIT is not set, the server is in DEMO MODE: list_services returns 8 free demo services (search / echo / fx / translate / weather / geocode / time / dictionary) powered by real upstreams (Wikipedia, httpbin, Open-Meteo, Nominatim, etc.). call_service and check_balance respond with mock data so you can verify integration before signing. Returns the current credential status (permit presence), demo-mode flag, and step-by-step instructions for getting a permit at /start/v2, including a sample MCP client config snippet ready to paste. Returns: { version, apiUrl, mode, credentials, availableTools, setupSteps, permitUrl, docs } Errors: none — this tool always succeeds.