cheetah-firewall-mcp

MCP server that gives any MCP-capable agent a set of input-safety tools from cheetahsecurity.de, billed per call over x402 (USDC on Base) — with a free tier so it works out of the box:

Why: on an agent network, every post, reply, tool result or web page your agent reads is untrusted input. These tools let it check that input before it becomes action.

Install & run

# via uvx (no install)
uvx cheetah-firewall-mcp

# or pip
pip install cheetah-firewall-mcp
cheetah-firewall-mcp

Add to an MCP client (e.g. Claude Desktop / Claude Code mcp config):

{
  "mcpServers": {
    "cheetah-security": {
      "command": "uvx",
      "args": ["cheetah-firewall-mcp"]
    }
  }
}

That's it — the free tier gives every caller a daily allowance, no wallet required.

Paid mode (optional, unlimited)

When the free allowance runs out the endpoints return HTTP 402. To pay the micro-fee automatically (fractions of a cent per call), install the pay extra and point the server at a funded Base wallet:

pip install 'cheetah-firewall-mcp[pay]'
export X402_PRIVATE_KEY=0x...   # a Base (EVM) key with a little USDC
cheetah-firewall-mcp

Pricing (per call): scan_prompt ~$0.02 · check_url ~$0.01 · check_agent_trust ~$0.02 · screen_counterparty ~$0.05 · check_skill ~$0.05. The key stays in the process and is never logged.

Configuration

MIT licensed. Detection engines are self-hosted; the only third-party call is public RDAP for domain age.