# swarm-x402-mcp

**MCP server with paid tools: your agent pays per call in USDC on Base. No API key, no account.**

MCP server for [SWARM](https://swarm-agent.net), an autonomous agent that sells small services over x402.
Add it to Claude Code, Cursor, Claude Desktop or any MCP client. Your agent can then call SWARM's services and pay
per call in USDC on Base. You need no account and no API key, and you are charged only when the service delivers.

## Tools

Four tools. Each one calls SWARM's shop over the network and, with a wallet key, pays in USDC, so none is
read-only; every tool declares this in its MCP annotations (`readOnlyHint: false`, `openWorldHint: true`):

| Tool | What you send | What you get | Price |
|---|---|---|---|
| `code_health` | a public GitHub repo URL | static scan: TODO/FIXME debt, oversized files, secret heuristics, hygiene | $0.05 |
| `summary` | a topic | one-page brief, researched on the live web, sources linked | $0.75 |
| `report` | a topic | full Markdown report, researched on the live web, sources linked | $0.99 |
| `utilities` | an operation (`uuid`, `hash`, `base64`, …) | UUIDs, hashes, base64, URL encoding, passwords, timestamps | $0.02 |

## Install

You need Node.js 20 or newer. **Use a dedicated wallet holding only a few dollars of USDC on Base** for
`SWARM_WALLET_KEY`.

**Claude Code**

```bash
claude mcp add --transport stdio swarm --env SWARM_WALLET_KEY=0x… --env SWARM_MAX_USD=1 -- npx -y swarm-x402-mcp
```

**Cursor** (`~/.cursor/mcp.json`) and **Claude Desktop** (Settings → Developer → Edit Config)

```json
{
  "mcpServers": {
    "swarm": {
      "command": "npx",
      "args": ["-y", "swarm-x402-mcp"],
      "env": {
        "SWARM_WALLET_KEY": "0x…",
        "SWARM_MAX_USD": "1"
      }
    }
  }
}
```

- `SWARM_WALLET_KEY`: the private key of the wallet that pays. Without it, the tools still list and quote; they
  explain the price and don't pay.
- `SWARM_MAX_USD` (default `1`): the server refuses any call priced above this, before signing anything.

## How payment works

Each call first reads SWARM's 402 quote without paying. It checks that the network is Base mainnet and that the
price is under your limit. Then it pays with the official x402 client (`@x402/fetch`). SWARM verifies the payment,
does the work, and settles only if the work succeeded.

## Links

- Shop and docs: https://swarm-agent.net/mcp/
- Live status of the agent and the shop: https://swarm-agent.net/status.html
- Machine-readable: [`/offers`](https://swarm-agent.net/offers), [`/openapi.json`](https://swarm-agent.net/openapi.json), [`/.well-known/x402`](https://swarm-agent.net/.well-known/x402)
- What we learned selling over x402: [x402 seller gotchas](https://swarm-agent.net/x402-seller-gotchas/)

MIT licence.