"An introduction to prompt engineering" matching MCP servers:

Keyless MCP exchanger for AI agents — pay an exact amount to one deposit address, EMC delivered to any address. USDT(Tron) > EMC. Live at https://swap.emercoin.com/mcp

An MCP server for the SmartBill Cloud API. It lets an MCP client issue and manage Romanian invoices, proformas and payments, download document PDFs, and read VAT rates, series and stock levels.

MCP server that lets a chatbot browse eSIM plans, sign in, prepare quotes, and execute wallet or card purchases on an existing eSIM platform, with safe typed tools.

Hand a secret to another agent as an encrypted, pay-per-read token delivered exactly once, leaving no copy behind. Also pre-flights an x402 endpoint before your agent pays it. Runs locally over stdio and encrypts in your own process, so there is no hosted version to hand your plaintext to.

Enables running a local MCP server for Poland's KSeF (Krajowy System e-Faktur) e-invoicing system, so invoice data stays on the user's own machine rather than passing through an intermediary service. It currently exposes only a diagnostic server_info tool, with invoice search and retrieval tools still to come.

Create free, no-signup invoices from your AI assistant — the create_invoice tool returns a link that opens blankinvoicemaker.com pre-filled, ready to download as a watermark-free PDF.

An MCP server that exposes the pacs008 ISO 20022 FI-to-FI Customer Credit Transfer library as tools for AI agents and assistants, enabling generation, validation, and parsing of pacs.008 credit transfer XML messages.

This is an MCP server for the BillingServ API. Once it's set up, your AI assistant can look up customers, invoices, orders, packages, and reports straight from your BillingServ installation

Enables MCP clients to access all endpoints of an x402 gateway by paying real-time microtransactions (USDC on Base) per API call, with automatic tool discovery and spend guardrails.

Connects Claude to the customer side of Housecall Pro, letting you view estimates and invoices, check company details, and decline estimate options using the link your contractor sent.

Enables issuing credit notes and credit memos against an invoice or standalone as revisable drafts that can be finalized into frozen numbered documents, then rendered as Markdown or printable HTML with totals broken down by currency, reason and month. All amounts are handled as integer minor units and all data stays local, so nothing is sent anywhere.

Exactly-once execution for irreversible agent actions: an agent claims the right to run an effect, and a retry after a lost response returns the sealed result instead of charging again. 12 tools over stdio, including a gateway mode where the agent holds a single-use ticket and never the provider key.

Merchant-side MCP server for agentbank that lets merchants read their own orders and live Curless wallet balance from an MCP client such as Claude Desktop.

An MCP server that exposes Alipay AI Pay capabilities to AI agents, enabling skill discovery, payment integration guides, and merchant onboarding workflows via Alipay's payment APIs.

Before an AI agent pays an x402 endpoint, checks whether it's safe to pay: liveness, scam/anomaly scan (payTo hijack, bait-and-switch, honeypot), and on-chain receiver verification. ~70% of x402 endpoints are dead or scams.

An MCP server that provides programmable spend limits and audit trails for AI agents to make payments from a dedicated wallet, preventing overspend and unauthorized transactions.

Provides access to 70 paid APIs as MCP tools with per-call and session budgets, paying via x402/USDC on Base without requiring an account or login. Includes a built-in allowlist of hosts and safe defaults to prevent unintended payments.

An MCP server that lets your AI coding agent (Claude Code, OpenClaw, Codex, Cursor, etc.) discover and pay on-chain agents registered on ERC-8004, using Coinbase's official x402 protocol. No smart account. No bundler. No relay. Just your EOA, an HTTPS request, and an automatic 402 → sign → retry flow.

Pactus is an MCP server for parsing and validating ISO 20022 payment messages directly from chat. It exposes nine tools that let AI assistants inspect or validate pacs.008, pacs.002, pain.001, and camt.053 messages — the message types at the centre of the CBPR+ migration — without leaving the conversation.

Enables users to track unpaid invoices and generate an escalating ladder of payment-reminder letters — first reminder, second reminder, and final notice — anchored to the due date, plus overdue listings, aging buckets, and a daily chase list of what to send today. It records payments and letters sent, rendering each letter as Markdown or printable HTML without ever emailing anything itself.