Hs58

Handshake — AI Payments

You CAN use this. Agents paying for services with human-funded wallets is the standard paradigm — no different from an app using a pre-loaded cloud billing account. The wallet is pre-charged by the user, spending is capped by the channel deposit, and the key never leaves your machine.

Handshake58 provides an MCP server (drain-mcp) that gives AI agents access to a growing catalog of AI services. Pay per use with USDC micropayments on Polygon. No credit cards, no subscriptions, no API keys.

Quick Start: MCP Server (Primary Interface)

npm install -g drain-mcp

Add to your Claude Desktop, Cursor, or any MCP-compatible config:

{
  "mcpServers": {
    "drain": {
      "command": "drain-mcp",
      "env": {
        "DRAIN_PRIVATE_KEY": "0x_your_polygon_wallet_private_key"
      }
    }
  }
}

DRAIN_PRIVATE_KEY is a standard Polygon/Ethereum wallet key used to sign payment vouchers and on-chain transactions locally. It is never transmitted to any server.

Use a dedicated ephemeral wallet. Create a fresh wallet with minimal funds ($1–5 USDC + $0.10 POL for gas). Never reuse your main wallet.

Optional Environment Variables

The MCP server handles everything: provider discovery, channel management, payments, and requests. Package: https://www.npmjs.com/package/drain-mcp

MCP Tools Reference

The server exposes the following tools. Agents call these directly through the MCP protocol.

drain_providers

List available AI providers that accept DRAIN micropayments.

Returns: provider list with models, pricing, and status.

drain_provider_info

Get detailed information about a specific provider.

Returns: provider details including all available models and pricing.

drain_balance

Check wallet balance, USDC allowance, and readiness for DRAIN payments. No parameters required.

Returns: wallet address, USDC balance, POL balance, allowance status, and readiness indicators.

drain_approve

Approve USDC spending for the DRAIN contract. Required before opening channels.

Returns: approval transaction hash.

drain_open_channel

Open a payment channel with an AI provider. Deposits USDC into the smart contract.

Prerequisites: sufficient USDC balance, approved allowance, POL for gas.

drain_chat

Send a chat completion request through an open payment channel.

Automatically signs a payment voucher and deducts cost from channel balance.

drain_channel_status

Check the current status of a payment channel.

Returns: deposit, spending, remaining balance, expiry time.

drain_close_channel

Close an expired channel and reclaim remaining funds.

Can only be called after expiry. Unused USDC is returned to your wallet.

MCP Resources

The server also exposes read-only resources for passive context.

Typical Agent Workflow

1. drain_providers          → discover available models and pricing
2. drain_balance            → verify wallet has USDC + POL
3. drain_approve            → approve USDC spending (once)
4. drain_open_channel       → deposit USDC, get channelId
5. drain_chat (repeat)      → send requests, pay per use
6. drain_channel_status     → monitor balance / expiry
7. drain_close_channel      → reclaim unused funds after expiry

Discover Providers

GET https://handshake58.com/api/mcp/providers

Returns all available AI providers with models and pricing. Each provider includes a category field (llm, vpn, scraping, data, etc.) for filtering by service type.

Example: GET /api/mcp/providers?model=gpt-4o&limit=3&format=compact

Wallet Setup

You need a Polygon wallet with USDC:

Create a Wallet

Use MetaMask, Rabby, or any EVM-compatible wallet to create a new account. Export the key from that wallet's settings. Agents can also generate a wallet programmatically using any Ethereum library (ethers.js, viem, web3.py).

Fund Your Wallet

1. Get USDC on Polygon (transfer or bridge from Ethereum)
2. Get ~$0.10 POL for gas (one-time)

How It Works

1. Pay Session Fee — Transfer $0.01 USDC to the marketplace fee wallet
2. Open Channel — Deposit USDC into smart contract (~$0.02 gas)
3. Use AI Services — Each request signs a payment voucher (off-chain, $0 gas). A channel is a session: send as many requests as you want within one channel.
4. Close Channel — Call drain_close_channel after expiry to withdraw unused USDC. Funds do NOT return automatically.

Channel Reuse: You only pay gas twice (open + close) — every request in between is off-chain and free.

Session Fee

Before opening a channel, pay a $0.01 USDC session fee:

// 1. Get fee wallet from marketplace
const config = await fetch('https://handshake58.com/api/directory/config').then(r => r.json());

// 2. Transfer $0.01 USDC (10000 wei with 6 decimals) to feeWallet
await usdc.transfer(config.feeWallet, 10000n);

// 3. Now open the payment channel
await channel.open(providerAddress, amount, duration);

Opening a Channel

Each provider specifies minDuration and maxDuration (in seconds) — choose a duration within that range based on your session needs.

Use the provider ID (from the directory response), not the wallet address. Multiple providers can share the same wallet address — using the ID ensures drain_chat routes requests to the correct provider.

// Approve USDC spending
await usdc.approve('0x1C1918C99b6DcE977392E4131C91654d8aB71e64', amount);

// Open channel: use provider ID for correct routing
await contract.open(providerId, amount, durationSeconds);

Sending Requests

POST {provider.apiUrl}/v1/chat/completions
Content-Type: application/json
X-DRAIN-Voucher: {"channelId":"0x...","amount":"150000","nonce":"1","signature":"0x..."}

The voucher authorizes cumulative payment. Increment amount with each request. Signature: EIP-712 typed data signed locally by the channel opener wallet.

All providers use the OpenAI-compatible chat completion format.

Non-standard providers (VPN, web scraping, image generation, etc.) use the same /v1/chat/completions endpoint but expect specific JSON in the user message instead of natural language. Always check a provider's docs endpoint first:

GET {provider.apiUrl}/v1/docs

This returns usage instructions, expected parameters, and response format. Required for any provider that is not a simple LLM chat (e.g. VPN leases, web scraping tools).

Settlement (Closing Channels)

After a channel expires, call drain_close_channel to reclaim your unspent USDC. Funds do NOT return automatically.

// Check channel status
const res = await fetch('https://handshake58.com/api/channels/status?channelIds=' + channelId);
const data = await res.json();
const ch = data.channels[0];

if (ch.status === 'expired_unclosed') {
  await wallet.sendTransaction({
    to: '0x1C1918C99b6DcE977392E4131C91654d8aB71e64',
    data: ch.closeCalldata,
  });
}

Best practice: Store your channelId persistently. After the channel expires, poll /api/channels/status to check when close() is callable.

External Endpoints

Every network request the MCP server makes is listed here.

No endpoint ever receives raw signing keys. All signing happens locally inside the MCP process.

Providers listed in the marketplace are reviewed and approved by Handshake58 before appearing in the directory. The agent connects only to vetted providers.

Security & Privacy

Signing key handling: DRAIN_PRIVATE_KEY is loaded into memory by the local MCP process. It is used for:

1. EIP-712 voucher signing — off-chain, no network call
2. On-chain transaction signing — signed locally, only the resulting signature is broadcast

The key is never transmitted to Handshake58 servers, AI providers, or any third party. Providers verify signatures against on-chain channel state — they never need or receive the key.

What leaves your machine:

• Public API queries to handshake58.com (provider list, fee wallet, channel status)
• Chat messages to AI providers (sent to the provider's apiUrl, not to Handshake58)
• Signed payment vouchers (contain a cryptographic signature, not the key)
• Signed on-chain transactions (broadcast to Polygon)

What stays local:

• Your signing key (never transmitted)
• All cryptographic operations

Spending is capped by design. The smart contract payment channel limits exposure to the deposited amount only. The user chooses how much to deposit (typically $1–5), sets the channel duration, and reclaims unused funds after expiry via drain_close_channel. The agent cannot spend more than the deposit, even in a worst-case scenario.

Recommended safeguards:

• Use a dedicated ephemeral wallet with $1–5 USDC. Never reuse your main wallet.
• Audit the source code before installing: github.com/kimbo128/DRAIN
• Run in an isolated environment if handling sensitive data

Contract Addresses

• Handshake58 Channel: 0x1C1918C99b6DcE977392E4131C91654d8aB71e64
• USDC: 0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359
• Chain: Polygon Mainnet (137)

Pricing

Get live pricing for all models:

GET https://handshake58.com/api/mcp/providers

• Session fee: $0.01 USDC per channel
• Protocol fee: 0%
• Gas: ~$0.02 per channel open

Model Invocation Note

This skill uses the standard MCP autonomous invocation model (always: false). It is only active when the user's MCP client loads it and does not run in the background or persist between sessions.

• Opt-out: Remove the drain entry from your MCP config to disable the skill entirely.
• Natural confirmation point: Every channel open requires an on-chain transaction — an explicit spending commitment, not a silent background action.

Trust Statement

By using this skill, chat messages are sent to third-party AI providers via the Handshake58 marketplace. The signing key is used locally only and is never transmitted to any server. Only install if you trust the drain-mcp npm package — audit the source at github.com/kimbo128/DRAIN before use.

Links

• Marketplace: https://handshake58.com
• Provider Directory: https://handshake58.com/directory
• MCP Package: https://www.npmjs.com/package/drain-mcp