Security & Controls

Walleot manages approvals and authentication as part of the MCP payment flow.

Approval behavior

• Under‑threshold charges may be auto‑approved for a seamless experience.
• Over‑threshold charges trigger a one‑tap approval (2FA prompt) to the user.
• New users are onboarded via a 2‑click registration flow.

These behaviors are handled by Walleot. Your MCP server only needs to set a price on each tool (see Quickstart and MCP Integration).

Modes

Both SDKs support multiple modes via an enum:

• TWO_STEP (default)
• RESUBMIT
• ELICITATION
• PROGRESS
• DYNAMIC_TOOLS

Pick the mode that best matches the MCP Clients who will use your MCP Server. For most cases, Mode.TWO_STEP is a sensible default.

The current list of client capabilities can be found here: https://modelcontextprotocol.io/clients

Example: set mode and price

Node.js

import { Server } from "@modelcontextprotocol/sdk/server";
import { installWalleot, Mode } from "walleot";
import { z } from "zod";

const server = new Server({ name: "my-server", version: "0.0.1" });

installWalleot(server, {
  apiKey: process.env.WALLEOT_API_KEY!,
  mode: Mode.TWO_STEP, 
});

server.registerTool(
  "add",
  {
    title: "Add",
    description: "Add two numbers.",
    inputSchema: { a: z.number(), b: z.number() },
    price: { amount: 0.19, currency: "USD" },
  },
  async ({ a, b }, extra) => {
    return { content: [{ type: "text", text: String(a + b) }] };
  }
);

Python

from mcp.server.fastmcp import FastMCP, Context
from walleot import Walleot, Mode
import os

mcp = FastMCP("My Server")

walleot = Walleot(
    mcp,
    apiKey=os.getenv("WALLEOT_API_KEY"),
    mode=Mode.TWO_STEP,
)

@walleot.price(0.19, currency="USD")
@mcp.tool()
def add(a: int, b: int, ctx: Context) -> int:
    return a + b

Note

• Add per‑tool prices: see Quickstart and MCP Integration.
• Walleot automatically includes pricing in your tool description, ensuring users are not surprised.