paymcp 0.2.0

Provider-agnostic payment layer for MCP (Model Context Protocol) tools and agents.

PayMCP

Provider-agnostic payment layer for MCP (Model Context Protocol) tools and agents.

paymcp is a lightweight SDK that helps you add monetization to your MCP-based tools, servers, or agents. It supports multiple payment providers and integrates seamlessly with MCP's tool/resource interface.

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🔧 Features

• ✅ Add @price(...) decorators to your MCP tools to enable payments
• 🔁 Choose between different payment flows (elicit, confirm, etc.)
• 🔌 Pluggable support for providers like Walleot, Stripe, and more
• ⚙️ Easy integration with FastMCP or other MCP servers

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🧭 Payment Flows

The payment_flow parameter controls how the user is guided through the payment process. Choose the strategy that fits your use case:

• PaymentFlow.TWO_STEP (default)
  Splits the tool into two separate MCP methods.
  The first step returns a payment_url and a next_step method for confirmation.
  The second method (e.g. confirm_add_payment) verifies payment and runs the original logic.
  Supported in most clients.

• PaymentFlow.ELICITATION Sends the user a payment link when the tool is invoked. If the client supports it, a payment UI is displayed immediately. Once the user completes payment, the tool proceeds.

• PaymentFlow.PROGRESS
  Shows payment link and a progress indicator while the system waits for payment confirmation in the background. The result is returned automatically once payment is completed.

• PaymentFlow.OOB (Out-of-Band)
  Not yet implemented.

All flows require the MCP client to support the corresponding interaction pattern. When in doubt, start with TWO_STEP.

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🚀 Quickstart

Install the SDK from PyPI:

pip install mcp paymcp

Initialize PayMCP:

from mcp.server.fastmcp import FastMCP, Context
from paymcp import PayMCP, price, PaymentFlow
import os

mcp = FastMCP("AI agent name")
PayMCP(
    mcp,  # your FastMCP instance
    providers={
        "stripe": {"apiKey": os.getenv("STRIPE_API_KEY")},
    },
    payment_flow=PaymentFlow.TWO_STEP #or ELICITATION / PROGRESS
)

Providers: alternative styles (optional)

Instances instead of config (advanced):

import os
from paymcp.providers import WalleotProvider, StripeProvider

PayMCP(
    mcp,
    providers=[
        WalleotProvider(api_key=os.getenv("WALLEOT_API_KEY")),
        CoinbaseProvider(api_key=os.getenv("COINBASE_API_KEY")),
    ],
)
# Note: right now the first configured provider is used.

Custom provider (minimal):
Any provider must subclass BasePaymentProvider and implement create_payment(...) and get_payment_status(...).

from paymcp.providers import BasePaymentProvider

class MyProvider(BasePaymentProvider):

    def create_payment(self, amount: float, currency: str, description: str):
        # Return (payment_id, payment_url)
        return "unique-payment-id", "https://example.com/pay"

    def get_payment_status(self, payment_id: str) -> str:
        return "paid"

PayMCP(mcp, providers=[MyProvider(api_key="...")])

Use the @price decorator on any tool:

@mcp.tool()
@price(amount=0.19, currency="USD")
def add(a: int, b: int, ctx: Context) -> int:
    # `ctx` is required by the PayMCP tool signature — include it even if unused
    return a + b

Demo server: For a complete setup, see the example repo: python-paymcp-server-demo.

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🪟 Optional: WebView (STDIO)

Open the payment link in a native window when your MCP server is connected via the stdio transport (typical for local/desktop installs).

• Install: pip install paymcp[webview] (or pdm add paymcp[webview]).
• What it does: when a priced tool is invoked, PayMCP opens a lightweight in-app webview to the provider's payment_url so the user can complete checkout without leaving the client.
• Scope: applies only to stdio connections on the user's machine.
• Notes: requires a desktop environment.

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🧩 Supported Providers

• ✅ Adyen
• ✅ Coinbase Commerce
• ✅ PayPal
• ✅ Stripe
• ✅ Square
• ✅ Walleot
• 🔜 Want another provider? Open an issue or submit a pull request!

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📄 License

MIT License