Yes, Swarm X402 is free to use.

How do I install Swarm X402?

Swarm X402 is a local plugin. Install it using npm package: swarm-x402-mcp and add the generated configuration snippet to your AI app's MCP config file. Then restart your AI app.

Is Swarm X402 safe to use?

Yes. Swarm X402 passed MCP Marketplace's automated security scan with a score of 10/10 (low risk). Every server on MCP Marketplace is security-scanned before it's listed; see the full security report on this page for the findings and permissions.

What credentials does Swarm X402 need?

Swarm X402 requires the following credentials or environment variables: SWARM_WALLET_KEY, SWARM_MAX_USD. You can find setup instructions on the server detail page.

What AI apps work with Swarm X402?

Swarm X402 uses the Model Context Protocol (MCP) and works with any MCP-compatible AI app, including Claude, ChatGPT / Codex, Gemini, Copilot, Cursor, and more.

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Swarm X402 MCP Server

by swarm-agent-operator

Developer ToolsLow Risk10.0Local

Free

Pay-per-call x402 services from SWARM: repo scans, web research. USDC on Base.

About

Pay-per-call x402 services from SWARM: repo scans, web research. USDC on Base.

Security Report

10.0

Low Risk10.0Low Risk

Valid MCP server (2 strong, 3 medium validity signals). No known CVEs in dependencies. Package registry verified. Imported from the Official MCP Registry.

3 files analyzed · 1 issue found

Security scores are indicators to help you make informed decisions, not guarantees. Always review permissions before connecting any MCP server.

Permissions Required

This plugin requests these system permissions. Most are normal for its category.

HTTP Network Access

Connects to external APIs or services over the internet.

env_vars

Check that this permission is expected for this type of plugin.

What You'll Need

Set these up before or after installing:

Private key of a dedicated wallet with a little USDC on Base. Without it, tools only quote.Required

Environment variable: SWARM_WALLET_KEY

Refuse any call priced above this many dollars (default 1).Optional

Environment variable: SWARM_MAX_USD

How to Install

Add this to your MCP configuration file:

{
  "mcpServers": {
    "io-github-swarm-agent-operator-swarm-x402-mcp": {
      "env": {
        "SWARM_MAX_USD": "your-swarm-max-usd-here",
        "SWARM_WALLET_KEY": "your-swarm-wallet-key-here"
      },
      "args": [
        "-y",
        "swarm-x402-mcp"
      ],
      "command": "npx"
    }
  }
}

Documentation

View on GitHub

From the project's GitHub README.

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, 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

Six 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
`site_check`	a URL	is it up: HTTP status, final URL after redirects, response time, TLS errors	$0.002
`read_page`	a URL	the readable text of the page (menus, scripts and markup removed)	$0.002

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

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)

{
  "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.

AgentCash: npx agentcash add https://swarm-agent.net

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.

If a call fails

A failed call is a normal tool result with isError: true. Its first line says whether you were charged and whether a retry is safe, for example charged: no; retry: safe. The tool never retries on its own.

charged: no: nothing was settled (SWARM settles only after the work succeeds). A retry signs a new payment.
charged: yes: the receipt carries the transaction hash. Do not pay again; write to contact@swarm-agent.net with it.
charged: unknown: the connection broke after a payment was signed. Check your wallet before calling again.

A signed x402 payment can be settled only once (its EIP-3009 nonce), and SWARM's shop also refuses a nonce it has already settled, so the same signed payment can never be charged twice.