x402-tools MCP server (agent-audit + page-read)

A small, stateless remote MCP server on Cloudflare Workers. It gives MCP clients four read-only web tools that are paid per call in USDC on Base via x402, plus free previews. There is no signup and no API key.

• Hosted endpoint: https://mcp.agent-audit.workers.dev/mcp (streamable HTTP; JSON responses; no SSE stream)

• Docs for agents: https://mcp.agent-audit.workers.dev/llms.txt

• MCP Registry: io.github.agent-audit-x402/x402-tools

The server is a thin front for two existing x402 HTTP APIs run by the same operator, with the same payee:

• page-read

• agent-audit

Tools

Limits:

• JavaScript is not executed.

• Private, loopback and link-local targets are refused.

• Invalid input and failed fetches are not charged; payment settles only after a 2xx result.

• Audit grades measure protocol conformance, not whether a seller is legitimate.

Related MCP server: Secant Agent Research

How payment works (x402 over MCP)

This follows the x402 v2 MCP transport:

1. Call a paid tool without payment. The tool result has isError: true, and structuredContent is the x402 v2 PaymentRequired of the upstream HTTP endpoint:

   • scheme exact, network eip155:8453;

   • asset USDC 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913, amount in atomic units (6 decimals);

   • payTo 0xa31bE3a1Ac1dde980dB8D18D32E7cd9Ab557360A, maxTimeoutSeconds 120.

   The same JSON is in content[0].text, and content[1] has plain-language payment steps.

2. Sign an EIP-3009 transferWithAuthorization for exactly that amount with any x402 v2 client, for example @x402/fetch or @x402/mcp with @x402/evm. Then call the tool again with the same arguments and the PaymentPayload in params._meta["x402/payment"]. For clients that can't set _meta, put it in the payment argument instead, as an object or as base64 JSON.

3. The server forwards the payment unchanged to the upstream API as the PAYMENT-SIGNATURE header. The upstream API verifies it with the facilitator (PayAI), runs the call, and settles only on success. The receipt {success, transaction, network, payer} comes back in result._meta["x402/payment-response"].

Further notes:

• The facilitator pays gas, so the buyer needs no ETH.

• If the payment status is uncertain, check USDC authorizationState(payer, nonce) on Base before signing a new payment.

• This server never pays, never charges by itself, holds no keys, and never returns a paid result without a settled payment.

Try it

curl -s https://mcp.agent-audit.workers.dev/mcp \
  -H 'content-type: application/json' -H 'accept: application/json, text/event-stream' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

# unpaid paid-tool call -> x402 PaymentRequired
curl -s https://mcp.agent-audit.workers.dev/mcp -H 'content-type: application/json' \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"read_page","arguments":{"url":"https://example.com"}}}'

# MCP Inspector CLI
npx @modelcontextprotocol/inspector --cli https://mcp.agent-audit.workers.dev/mcp --transport http --method tools/list

MCP client config:

{ "mcpServers": { "x402-tools": { "url": "https://mcp.agent-audit.workers.dev/mcp" } } }

Self-hosting

The code has no runtime dependencies: one file, src/index.js. It reaches the two upstream workers through Cloudflare service bindings (AUDIT, READ in wrangler.toml). Without bindings it falls back to plain fetch of the public URLs. To run your own copy:

npm install
export CLOUDFLARE_API_TOKEN=...      # your own token; never commit it
export CLOUDFLARE_ACCOUNT_ID=...     # your own account id
npx wrangler deploy

No secrets are needed or stored. Set PAY_TO in wrangler.toml only for display; the payee in each challenge comes from the upstream API.

Operator

Run by the GitHub account agent-audit-x402, the shared official account for agent-audit and page-read. Contact: parafield-dev@mail.grokbot.com.

Listed in the x402 Blockchains registry. There are no customer sales yet.

License

MIT