--- name: clawdirect-dev description: Build agent-facing web experiences with ATXP-based authentication, following the ClawDirect pattern. Use this skill when building websites that AI agents interact with via MCP tools, implementing cookie-based agent auth, or creating agent skills for web apps. Provides templates using @longrun/turtle, Express, SQLite, and ATXP. ---

ClawDirect-Dev

Build agent-facing web experiences with ATXP-based authentication.

Reference implementation: https://github.com/napoleond/clawdirect

What is ATXP?

ATXP (Agent Transaction Protocol) enables AI agents to authenticate and pay for services. When building agent-facing websites, ATXP provides:

• Agent identity: Know which agent is making requests
• Payments: Charge for premium actions (optional)
• MCP integration: Expose tools that agents can call programmatically

For full ATXP details: https://skills.sh/atxp-dev/cli/atxp

How Agents Interact

Agents interact with your site in two ways:

1. Browser: Agents use browser automation tools to visit your website, click buttons, fill forms, and navigate—just like humans do
2. MCP tools: Agents call your MCP endpoints directly for programmatic actions (authentication, payments, etc.)

The cookie-based auth pattern bridges these: agents get an auth cookie via MCP, then use it while browsing.

Important: Agent browsers often cannot set HTTP-only cookies directly. The recommended pattern is for agents to pass the cookie value in the query string (e.g., ?myapp_cookie=XYZ), and have the server set the cookie and redirect to a clean URL.

Architecture Overview

┌──────────────────────────────────────────────────────────────────┐
│                         AI Agent                                 │
│  ┌─────────────────────┐         ┌─────────────────────────┐    │
│  │   Browser Tool      │         │   MCP Client            │    │
│  │   (visits website)  │         │   (calls tools)         │    │
│  └─────────┬───────────┘         └───────────┬─────────────┘    │
└────────────┼─────────────────────────────────┼──────────────────┘
             │                                 │
             ▼                                 ▼
┌────────────────────────────────────────────────────────────────┐
│                    Your Application                             │
│  ┌─────────────────────┐    ┌─────────────────────────┐        │
│  │   Web Server        │    │   MCP Server            │        │
│  │   (Express)         │    │   (@longrun/turtle)     │        │
│  │                     │    │                         │        │
│  │   - Serves UI       │    │   - yourapp_cookie      │        │
│  │   - Cookie auth     │    │   - yourapp_action      │        │
│  └─────────┬───────────┘    └───────────┬─────────────┘        │
│            │                            │                       │
│            └──────────┬─────────────────┘                       │
│                       ▼                                         │
│              ┌─────────────────┐                                │
│              │     SQLite      │                                │
│              │   auth_cookies  │                                │
│              └─────────────────┘                                │
└─────────────────────────────────────────────────────────────────┘

Build Steps

1. Create MCP server alongside your website
2. Implement cookie tool in the MCP server
3. Use cookie for auth in your web API
4. Publish an agent skill for your site

Step 1: Project Setup

Initialize a Node.js project with the required stack:

mkdir my-agent-app && cd my-agent-app
npm init -y
npm install @longrun/turtle @atxp/server @atxp/express better-sqlite3 express cors dotenv zod
npm install -D typescript @types/node @types/express @types/cors @types/better-sqlite3 tsx

Create tsconfig.json:

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "NodeNext",
    "moduleResolution": "NodeNext",
    "outDir": "dist",
    "rootDir": "src",
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true
  },
  "include": ["src/**/*"]
}

Create .env:

FUNDING_DESTINATION_ATXP=<your_atxp_account>
PORT=3001

Step 2: Database with Cookie Auth

Create src/db.ts:

import Database from 'better-sqlite3';
import crypto from 'crypto';

const DB_PATH = process.env.DB_PATH || './data.db';
let db: Database.Database;

export function getDb(): Database.Database {
  if (!db) {
    db = new Database(DB_PATH);
    db.pragma('journal_mode = WAL');

    // Auth cookies table - maps cookies to ATXP accounts
    db.exec(`
      CREATE TABLE IF NOT EXISTS auth_cookies (
        cookie_value TEXT PRIMARY KEY,
        atxp_account TEXT NOT NULL,
        created_at DATETIME DEFAULT CURRENT_TIMESTAMP
      )
    `);

    // Add your app's tables here
  }
  return db;
}

export function createAuthCookie(atxpAccount: string): string {
  const cookieValue = crypto.randomBytes(32).toString('hex');
  getDb().prepare(`
    INSERT INTO auth_cookies (cookie_value, atxp_account)
    VALUES (?, ?)
  `).run(cookieValue, atxpAccount);
  return cookieValue;
}

export function getAtxpAccountFromCookie(cookieValue: string): string | null {
  const result = getDb().prepare(`
    SELECT atxp_account FROM auth_cookies WHERE cookie_value = ?
  `).get(cookieValue) as { atxp_account: string } | undefined;
  return result?.atxp_account || null;
}

Step 3: MCP Tools with Cookie Tool

Create src/tools.ts:

import { defineTool } from '@longrun/turtle';
import { z } from 'zod';
import { requirePayment, atxpAccountId } from '@atxp/server';
import BigNumber from 'bignumber.js';
import { createAuthCookie } from './db.js';

// Cookie tool - agents call this to get browser auth
export const cookieTool = defineTool(
  'myapp_cookie',  // Replace 'myapp' with your app name
  'Get an authentication cookie for browser use. Set this cookie to authenticate when using the web interface.',
  z.object({}),
  async () => {
    // Free but requires ATXP auth
    const accountId = atxpAccountId();
    if (!accountId) {
      throw new Error('Authentication required');
    }

    const cookie = createAuthCookie(accountId);

    return JSON.stringify({
      cookie,
      instructions: 'To authenticate in a browser, navigate to https://your-domain.com?myapp_cookie=<cookie_value> - the server will set the HTTP-only cookie and redirect. Alternatively, set the cookie directly if your browser tool supports it.'
    });
  }
);

// Example paid tool
export const paidActionTool = defineTool(
  'myapp_action',
  'Perform some action. Cost: $0.10',
  z.object({
    input: z.string().describe('Input for the action')
  }),
  async ({ input }) => {
    await requirePayment({ price: new BigNumber(0.10) });

    const accountId = atxpAccountId();
    if (!accountId) {
      throw new Error('Authentication required');
    }

    // Your action logic here
    return JSON.stringify({ success: true, input });
  }
);

export const allTools = [cookieTool, paidActionTool];

Step 4: Express API with Cookie Validation

Create src/api.ts:

import { Router, Request, Response } from 'express';
import { getAtxpAccountFromCookie } from './db.js';

export const apiRouter = Router();

// Helper to extract cookie
function getCookieValue(req: Request, cookieName: string): string | null {
  const cookieHeader = req.headers.cookie;
  if (!cookieHeader) return null;

  const cookies = cookieHeader.split(';').map(c => c.trim());
  for (const cookie of cookies) {
    if (cookie.startsWith(`${cookieName}=`)) {
      return cookie.substring(cookieName.length + 1);
    }
  }
  return null;
}

// Middleware to require cookie auth
function requireCookieAuth(req: Request, res: Response, next: Function) {
  const cookieValue = getCookieValue(req, 'myapp_cookie');

...