@hpp-io/x402-mcp-bridge

Name: HPP x402 MCP Bridge
Author: hpp-io

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

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

Tool	What it does
`wallet_address`	report your wallet address (to fund it)
`hpp_discover`	list/search the curated HPP directory (read-only)
`hpp_describe`	one service's input args — schema + example (read-only)
`hpp_call`	call a discovered service (HTTP/MCP/A2A); pays via your wallet
`x402_http_call`	pay + call any x402 HTTP endpoint
`pay_a2a_agent`	pay + message another A2A agent

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

Key env (all optional)

Var	Notes
`DELEGATE_PRIVATE_KEY`	auto-created in the OS keychain if unset
`HPP_NETWORK`	`eip155:181228` Sepolia (default) / `eip155:190415` Mainnet
`RESOURCE_SERVER_URL`	proxy one upstream MCP server (omit = local tools only)
`SAFE_ADDRESS` + `ALLOWANCE_MODULE_ADDRESS`	set both = Safe (governance) mode

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

HPP x402 MCP Bridge