Introspect the MCP's payment capabilities: which wallets are configured, spending limits, and stored credential count. Call this first to understand what payment methods are available.

Probe an endpoint to discover its L402 pricing without committing to payment. Returns the cost in sats, available payment methods, and credit tiers (if toll-booth server). The challenge is cached so a subsequent l402-pay can reuse it.

Fetch a URL, paying its HTTP 402 challenge (L402, IETF Payment, Cashu or LNURLcash) when autoPay is true and the price is within MAX_AUTO_PAY_SATS, maxCostSats and the spend limits. Reuses stored credentials. Without autoPay, a 402 comes back with its price and paymentHash so the user can decide; l402-pay can then pay it. For x402 services, which this server supports only in an experimental custom format, returns the payment details for the user to pay in their own wallet. Response bodies are marked as untrusted content. With widget hosts, call l402-fetch-preview first to show the price.

Pay a challenge that l402-fetch or l402-discover returned, by its paymentHash, and store the credential so the next l402-fetch succeeds. For human wallets, polls the payment page for settlement for up to 120s; call it straight after showing the payment URL to the user. An invoice that did not come from such a challenge is paid only if the human approves it in the client.

List all stored L402 credentials. Shows origin, cached credit balance, and server type. Balance values are cached and may be stale; check lastUsed timestamp.

Check cached credit balance for a server. Returns the last known balance from the credential store without making a network request. The "stale" flag is true if the balance was last updated more than 5 minutes ago.

Store an L402 token (macaroon:preimage) obtained from a payment page. Use this when a user pastes back a token from a toll-booth payment page. The token is stored as a credential so subsequent l402-fetch calls are authenticated.

Buy credits from a toll-booth server with volume discounts. Omit amountSats to discover available tiers. Provide amountSats to purchase a specific tier. Only works with toll-booth servers.

Resolve a payment whose outcome is unknown. While one is unresolved, auto-pay to that service is paused. Call with no arguments to list them, or with a paymentHash to ask the wallet (NWC lookup_invoice, or the Cashu mint for a reserved melt). A settled payment stores its credential when it can; a failed one is cleared. A preimage that hashes to the payment hash also settles it. abandon: true asks the human to confirm that the payment did not go out.

Redeem Cashu ecash tokens directly on a toll-booth server, avoiding the Lightning round-trip. Handles the two-step flow automatically (create invoice then redeem token). Only works with toll-booth servers.

Search Nostr relays for paid API announcements (kind 31402) and return their URLs, pricing and capabilities. Topic and payment-method filters are sent to the relays; the query text is matched locally. Announcement text is written by whoever published it and is marked as untrusted content.

Preview payment requirements for a URL without spending any sats. Returns cost, protocol, and payment method so a confirmation dialog can be shown. Use this before l402-fetch to give the user a chance to approve or cancel payment. For widget hosts, the result drives a payment confirmation dialog.