Connect Your AI Assistant to Pay3: MCP Setup Guide

Connecting your AI assistant to Pay3 takes less than five minutes. You install nothing permanently — the MCP server runs on demand via npx each time your AI client starts. All you need is a Pay3 account, an active session, and the MCP auth token that session generates.

Prerequisites

Before you configure any AI client, make sure you have the following ready:

A Pay3 account. Sign up at pay3.finance if you haven’t already.
An active AI session with an MCP auth token. Open the Pay3 Dashboard, navigate to Sessions, create a new session, and copy the PAY3_MCP_AUTH_TOKEN.

Your PAY3_MCP_AUTH_TOKEN is shown only once when you create the session. Copy it immediately and store it somewhere safe — you cannot retrieve it again. If you lose it, you’ll need to create a new session.

Pay3 has two environments. Use the correct API_BASE_URL for your environment:

Testnet (sandbox): https://api-testnet.pay3.finance
Production: https://api.pay3.finance

MCP server configuration

Every MCP client uses the same underlying JSON configuration block. Fill in your token and target environment, then paste it into the location your client expects.

{
  "mcpServers": {
    "pay3": {
      "command": "npx",
      "args": ["-y", "@pay3/mcp-server"],
      "env": {
        "PAY3_MCP_AUTH_TOKEN": "<your-mcp-auth-token>",
        "API_BASE_URL": "https://api.pay3.finance"
      }
    }
  }
}

Replace <your-mcp-auth-token> with the token you copied from the Sessions dashboard.

Client setup

Claude Desktop
Cursor
Custom Agent (LangChain / AutoGen / CrewAI)

Claude Desktop reads its MCP server list from a single JSON config file on your machine. Follow these steps:

Locate the config file

Open (or create) the Claude Desktop config file at the path for your operating system:

~/Library/Application Support/Claude/claude_desktop_config.json

%APPDATA%\Claude\claude_desktop_config.json

Add the Pay3 MCP server

If the file already contains a mcpServers object, merge the pay3 entry into it. If the file is empty or doesn’t exist, paste the full block below:

claude_desktop_config.json

{
  "mcpServers": {
    "pay3": {
      "command": "npx",
      "args": ["-y", "@pay3/mcp-server"],
      "env": {
        "PAY3_MCP_AUTH_TOKEN": "<your-mcp-auth-token>",
        "API_BASE_URL": "https://api.pay3.finance"
      }
    }
  }
}

Restart Claude Desktop

Quit Claude Desktop completely and reopen it. When it starts, it will launch the Pay3 MCP server in the background. You should now see Pay3 tools available when you click the tool icon in the Claude chat interface.

Verify the connection

Type the following in a new Claude conversation to confirm everything is working:

What is my Pay3 USDC balance?

Claude will call get_balance and return your current balance.

Cursor has a built-in MCP Servers panel in its settings. No manual file editing is required.

Open MCP Settings

In Cursor, press Cmd + , (macOS) or Ctrl + , (Windows/Linux) to open Settings, then navigate to the MCP Servers section.

Add a new MCP server

Click Add MCP Server and enter the following values:

Field	Value
Name	`pay3`
Command	`npx`
Args	`-y @pay3/mcp-server`
`PAY3_MCP_AUTH_TOKEN`	Your token from the Sessions dashboard
`API_BASE_URL`	`https://api.pay3.finance`

Alternatively, switch to JSON mode in the MCP panel and paste the config block directly:

{
  "mcpServers": {
    "pay3": {
      "command": "npx",
      "args": ["-y", "@pay3/mcp-server"],
      "env": {
        "PAY3_MCP_AUTH_TOKEN": "<your-mcp-auth-token>",
        "API_BASE_URL": "https://api.pay3.finance"
      }
    }
  }
}

Restart Cursor

Save your settings and restart Cursor. The Pay3 MCP server will start automatically on the next launch and the three Pay3 tools will be available to the Cursor AI agent.

If you’re building your own agent with LangChain, AutoGen, CrewAI, or any framework that supports the MCP TypeScript SDK, connect via a stdio transport client.

Install the MCP SDK

Add the official MCP client SDK to your project:

npm install @modelcontextprotocol/sdk

Set environment variables

Export your Pay3 credentials before launching your agent process, or load them from a .env file:

.env

PAY3_MCP_AUTH_TOKEN=<your-mcp-auth-token>
API_BASE_URL=https://api.pay3.finance

Connect via stdio transport

Spawn the Pay3 MCP server as a child process and attach a stdio client:

import { Client } from "@modelcontextprotocol/sdk/client/index.js";
import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js";

const transport = new StdioClientTransport({
  command: "npx",
  args: ["-y", "@pay3/mcp-server"],
  env: {
    PAY3_MCP_AUTH_TOKEN: process.env.PAY3_MCP_AUTH_TOKEN!,
    API_BASE_URL: process.env.API_BASE_URL!,
  },
});

const client = new Client({ name: "my-agent", version: "1.0.0" });
await client.connect(transport);

// List available tools
const { tools } = await client.listTools();
console.log(tools.map((t) => t.name));
// → ["get_balance", "transfer", "get_transaction_history"]

Call a tool

Invoke any Pay3 tool directly from your agent logic:

const result = await client.callTool({
  name: "get_balance",
  arguments: { asset: "USDC" },
});

console.log(result.content);

Pass the client instance to your LangChain MCPToolkit, AutoGen tool adapter, or CrewAI tool wrapper to expose get_balance, transfer, and get_transaction_history as native agent tools.

Next steps

Now that your AI client is connected, explore what each tool can do:

MCP Tools Reference

See every parameter, execution outcome, and example AI prompt for all three Pay3 tools.

Sessions Dashboard

Manage your active sessions, set spending policies, and approve pending transactions.

Get Started

Core Concepts

Dashboard

MCP Integration

DeFi & Payments

Connect Your AI Assistant to Pay3: MCP Setup Guide

Prerequisites

MCP server configuration

Client setup

Next steps

MCP Tools Reference

Sessions Dashboard

​Prerequisites

​MCP server configuration

​Client setup

​Next steps

MCP Tools Reference

Sessions Dashboard

Prerequisites

MCP server configuration

Client setup

Next steps