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HPP x402 MCP Bridge

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MCP bridge for autonomous x402 payments in HPP USDC.e — discover and pay for services per call.

Source code Website Documentation

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

NPM package @hpp-io/x402-mcp-bridge
Claude Code 
claude mcp add hpp-x402-mcp-bridge -e 'DELEGATE_PRIVATE_KEY=<your delegate_private_key>' -e 'HPP_NETWORK=<HPP_NETWORK>' -e 'RESOURCE_SERVER_URL=<RESOURCE_SERVER_URL>' -e 'SAFE_ADDRESS=<SAFE_ADDRESS>' -e 'ALLOWANCE_MODULE_ADDRESS=<ALLOWANCE_MODULE_ADDRESS>' -- npx -y @hpp-io/x402-mcp-bridge@0.1.23
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "hpp-x402-mcp-bridge": {
            "command": "npx",
            "args": [
                "-y",
                "@hpp-io/x402-mcp-bridge@0.1.23"
            ],
            "env": {
                "DELEGATE_PRIVATE_KEY": "<your delegate_private_key>",
                "HPP_NETWORK": "<HPP_NETWORK>",
                "RESOURCE_SERVER_URL": "<RESOURCE_SERVER_URL>",
                "SAFE_ADDRESS": "<SAFE_ADDRESS>",
                "ALLOWANCE_MODULE_ADDRESS": "<ALLOWANCE_MODULE_ADDRESS>"
            }
        }
    }
}

Environment variables

  • DELEGATE_PRIVATE_KEY secret Delegate EOA private key used to sign payments. Auto-created in the OS keychain if unset.
  • HPP_NETWORK Target network: eip155:181228 (HPP Sepolia, default) or eip155:190415 (HPP Mainnet).
  • RESOURCE_SERVER_URL Optional upstream MCP server to proxy. Omit to expose only the local tools.
  • SAFE_ADDRESS Safe address for governance (Safe) mode. Set together with ALLOWANCE_MODULE_ADDRESS.
  • ALLOWANCE_MODULE_ADDRESS Safe AllowanceModule address for governance (Safe) mode. Set together with SAFE_ADDRESS.

Documentation

From the project's README on GitHub, refreshed weekly. Links open on GitHub.

Contents
  1. @hpp-io/x402-mcp-bridge
  2. 📖 Full documentation
  3. Install
  4. Quick start
  5. Use it from an MCP host
  6. Related
  7. License

@hpp-io/x402-mcp-bridge

The agent payment rail for HPP. A stdio MCP bridge + the hpp-x402 CLI that let Claude Desktop / Claude Code / Cursor / Windsurf / OpenClaw make autonomous HPP USDC.e payments over x402 — discover paid services, pay per call, within a spend cap. No API keys, no manual signing.

📖 Full documentation

hpp-io/x402-tools — the complete manual: how it works, every command, buyer and seller flows, payment schemes (exact / upto), wallet modes, and troubleshooting. This README is a quick reference.

Install

# macOS / Linux
curl -fsSL https://raw.githubusercontent.com/hpp-io/x402-tools/main/install/install.sh | bash
# Windows (PowerShell)
irm https://raw.githubusercontent.com/hpp-io/x402-tools/main/install/install.ps1 | iex
# …or npm
npm install -g @hpp-io/x402-mcp-bridge

Needs Node 20+. On a headless box (no OS keychain) use setup --print-key — see the manual.

Quick start

hpp-x402 setup --install claude-code   # create a wallet + register into your host
hpp-x402 fund                          # where to send USDC.e (gasless, no native gas)
hpp-x402 status                        # confirm it's wired

Restart your host and your agent can discover and pay for services. Browse and pay from the terminal too:

hpp-x402 discover "price prediction"               # semantic search; your network only
hpp-x402 describe <id>                             # input args (schema + example) — no payment
hpp-x402 call <url-or-id> --body '{"hi":"there"}'  # pay + call — a URL, or an id from discover
Pay from your HPP Smart Wallet instead

Rather than funding the agent's key, let it pay from your HPP Smart Wallet under a spending limit you set. In the wallet, open Agents → New, paste the agent's address (hpp-x402 wallet address), issue the delegation, then run the command the wallet shows — it is this, with the value filled in:

hpp-x402 install claude-code -n eip155:190415 --delegation 0x…

Run it on the machine where the agent's key lives. The value is checked against that key and the network before it is written, and again each time the bridge starts. The value can only be used by that key, within the limit, until it expires — but it does end up in your shell history, so treat it like a card with a cap. To stop the agent, revoke the delegation in the wallet.

Full command reference, selling (serve), schemes, and Safe mode → the manual.

Use it from an MCP host

The host spawns the bridge over stdio. A bare entry boots zero-config on HPP Sepolia with an auto-created keychain wallet:

{ "mcpServers": { "hpp-x402": {
  "command": "npx", "args": ["-y", "@hpp-io/x402-mcp-bridge"]
} } }

hpp-x402 install <host> writes this for you. Note: a bare npx @hpp-io/x402-mcp-bridge runs the MCP server (what the host wants) — for the CLI use npx -y -p @hpp-io/x402-mcp-bridge hpp-x402 <command>.

Host-facing tools
ToolWhat it does
wallet_addressreport your wallet address (to fund it)
hpp_discoverlist/search the curated HPP directory (read-only)
hpp_describeone service's input args — schema + example (read-only)
hpp_callcall a discovered service (HTTP/MCP/A2A); pays via your wallet
x402_http_callpay + call any x402 HTTP endpoint
pay_a2a_agentpay + message another A2A agent

Every paid call stays within your spend cap; discovery never holds funds or sees your keys.

Key env (all optional)
VarNotes
DELEGATE_PRIVATE_KEYauto-created in the OS keychain if unset
HPP_NETWORKeip155:181228 Sepolia (default) / eip155:190415 Mainnet
RESOURCE_SERVER_URLproxy one upstream MCP server (omit = local tools only)
SAFE_ADDRESS + ALLOWANCE_MODULE_ADDRESSset both = Safe (governance) mode
HPP_PAYMENT_DELEGATIONERC-7710 payment delegation a wallet granted to this key: pays erc7710 accepts from the user's smart account under on-chain caps — this key needs no USDC.e. hpp-x402 install <host> --delegation <value> writes it. Checked against the key and the network at install and at boot (a value issued on the other network, revoked, or expired stops the bridge with the reason); without it such accepts are skipped

Full environment reference + Safe/governance setup are in the manual.

Building an agent / SDK integration (LangChain, OpenAI function-calling, AgentKit, A2A)? See the runnable gallery → hpp-io/hpp-x402-agent-sample

License

Apache-2.0

Frequently asked questions

What is HPP x402 MCP Bridge?

MCP bridge for autonomous x402 payments in HPP USDC.e — discover and pay for services per call.

How do I install HPP x402 MCP Bridge?

It runs on your machine. In Claude Code: claude mcp add hpp-x402-mcp-bridge -e 'DELEGATE_PRIVATE_KEY=<your delegate_private_key>' -e 'HPP_NETWORK=<HPP_NETWORK>' -e 'RESOURCE_SERVER_URL=<RESOURCE_SERVER_URL>' -e 'SAFE_ADDRESS=<SAFE_ADDRESS>' -e 'ALLOWANCE_MODULE_ADDRESS=<ALLOWANCE_MODULE_ADDRESS>' -- npx -y @hpp-io/x402-mcp-bridge@0.1.23. For other clients, paste the JSON configuration from this page into their MCP settings.

Does HPP x402 MCP Bridge need an API key?

Yes. It expects DELEGATE_PRIVATE_KEY, which you set in its configuration.

Is HPP x402 MCP Bridge open source?

Its code is public on GitHub, but the repository does not declare a standard license.

Who maintains HPP x402 MCP Bridge?

It is published by hpp-io. AI.tn lists it but does not maintain or endorse it.

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