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<h1 align="center">@three-ws/x402-mcp</h1>
<p align="center"><strong>Give any AI agent a self-custodial x402 wallet — discover, inspect, and pay any paid service in USDC from your own Solana key.</strong></p>
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---
> A [Model Context Protocol](https://modelcontextprotocol.io) server that turns any AI assistant into an autonomous economic agent on the [x402](https://x402.org) network. Search the live bazaar for paid services, read an endpoint's price **before** committing money, and `pay_and_call` any x402 service in USDC — settled on Solana with **your own key**, never a custodial wallet.
This is the *buyer* side of the three.ws agent economy. The payment dance and Solana `exact`-scheme signing are handled by the real `@x402/*` libraries — nothing is mocked.
## Install
```bash
npm install @three-ws/x402-mcp
```
Or run with `npx`:
```bash
SOLANA_SECRET_KEY=<base58> npx @three-ws/x402-mcp
```
## Quick start
**Claude Code**, one line:
```bash
claude mcp add x402 --env SOLANA_SECRET_KEY=<base58> -- npx -y @three-ws/x402-mcp
```
**Claude Desktop / Cursor** (`claude_desktop_config.json` or `mcp.json`):
```json
{
"mcpServers": {
"x402": {
"command": "npx",
"args": ["-y", "@three-ws/x402-mcp"],
"env": {
"SOLANA_SECRET_KEY": "<base58 secret of the wallet that holds USDC>",
"SOLANA_RPC_URL": "https://your-rpc-provider",
"MAX_PAY_USD": "1"
}
}
}
}
```
`SOLANA_SECRET_KEY` is only needed to **spend** (`pay_and_call`, and `x402_wallet` defaulting to your wallet). `find_services` and `inspect_endpoint` work with no key.
## Tools
| Tool | Type | What it does |
| ------------------ | ------------- | -------------------------------------------------------------------------------------------------------- |
| `x402_wallet` | read-only | A wallet's address + live SOL/USDC balance. Defaults to your signer wallet — confirm funds before paying. |
| `find_services` | read-only | Search the live x402 bazaar (PayAI + Coinbase CDP) for paid HTTP/MCP services with prices. |
| `inspect_endpoint` | read-only | Read any endpoint's 402 payment requirements (scheme, network, asset, price, pay-to) **without paying**. |
| `pay_and_call` | **execution** | Pay an x402 endpoint in USDC from your Solana key and return its result. Bounded by `MAX_PAY_USD`. |
### Safety
`pay_and_call` carries `destructiveHint: true`, so annotation-aware clients (Claude Code, Claude Desktop, Cursor) prompt before running it. Beyond the client hint, every payment is bounded server-side: it **probes the 402 first** and refuses if the price exceeds `max_usd` or `MAX_PAY_USD` (default $1) **before any money moves**, and with `REQUIRE_CONFIRM` on (default) the call refuses until re-issued with `confirm: true`. Only the Solana (`solana:*`) `exact`-scheme requirement is settled — with the key you control.
### Input parameters
**`x402_wallet`** — `address` (optional base58; defaults to the signer wallet).
**`find_services`** — `query` (required), `type` (`http` | `mcp`, default `http`), `network` (CAIP-2 filter), `max_price_usdc`, `limit` (1–100).
**`inspect_endpoint`** — `url` (required), `method` (`GET` | `POST`), `body` (object).
**`pay_and_call`** — `url` (required), `method` (`GET` | `POST`), `body` (object), `max_usd` (lowers the cap for this call), `secret` (per-call signer override), `confirm` (must be `true` when `REQUIRE_CONFIRM` is on).
## Example
```jsonc
// inspect_endpoint — what does it cost? (no payment)
> { "url": "https://three.ws/api/x402/vanity?prefix=ab" }
{
"ok": true, "paid": true,
"accepts": [
{ "scheme": "exact", "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp", "asset": "EPjFW…", "price": 50000 }
],
"payable_with_this_wallet": true
}
// pay_and_call — confirm:true required by default
> { "url": "https://three.ws/api/x402/vanity?prefix=ab", "confirm": true }
{ "ok": true, "paid": true, "payer": "Gx5E…", "price_usd": 0.05, "settlement": { … }, "result": { … } }
```
## Requirements
- **Node.js >= 20.**
- A Solana mainnet RPC endpoint (`https`; only `http://localhost` is allowed for dev). Public cluster works for reads; bring your own for payment traffic.
- To pay: a Solana wallet holding USDC, as a base58 `SOLANA_SECRET_KEY` (or per-call `secret`).
### Environment variables
| Variable | Required | Default |
| ------------------- | ------------ | ------------------------------------- |
| `SOLANA_SECRET_KEY` | to pay only | — |
| `SOLANA_RPC_URL` | no | `https://api.mainnet-beta.solana.com` |
| `MAX_PAY_USD` | no | `1` |
| `REQUIRE_CONFIRM` | no | `true` |
| `THREE_WS_BASE` | no | `https://three.ws` |
## Links
- Homepage: https://three.ws
- MCP catalog: https://three.ws/docs/mcp
- Changelog: https://three.ws/changelog
- Issues: https://github.com/nirholas/three.ws/issues
- License: Apache-2.0 — see [LICENSE](./LICENSE)
---
<p align="center">
<sub>
Part of the <a href="https://three.ws">three.ws</a> SDK suite — 3D AI agents, on-chain identity, and agent payments.<br/>
<a href="https://three.ws">Website</a> · <a href="https://three.ws/changelog">Changelog</a> · <a href="https://github.com/nirholas/three.ws">GitHub</a>
</sub>
</p>
## License
Copyright © 2026 nirholas. All rights reserved.
This software is proprietary — see [LICENSE](./LICENSE). No rights are granted
without the express written permission of the copyright owner.
