# x402 Wallet (MCP server)

> x402 Wallet is an MCP server that adds finance tools to AI assistants such as Claude Desktop, Claude Code and Cursor. Self-custodial x402 wallet for AI agents: pay any service in USDC or $THREE from your own key. It has 250 GitHub stars, is released under the Apache-2.0 license and runs locally with npx -y @three-ws/x402-mcp.

Give any AI agent a self-custodial x402 wallet — discover, inspect, and pay any paid service in USDC from your own Solana key.

## Key facts

| Fact | Value |
|---|---|
| Repository | https://github.com/nirholas/three.ws |
| GitHub stars | 250 |
| License | Apache-2.0 |
| Language | JavaScript |
| Transport | stdio |
| Packages | npm: @three-ws/x402-mcp |
| Remote URL | none |
| Needs API key | yes |
| Official | no |
| Works with | Claude Desktop, Claude Code, Cursor, VS Code |
| Category | Finance |
| Latest release | forge-v0.5.0 (Oct 11, 2026) |
| Last commit | Oct 25, 2026 |
| MCP registry name | io.github.nirholas/x402-mcp |

## Install

### Claude Desktop (claude_desktop_config.json)

```json
{
  "mcpServers": {
    "x402-wallet": {
      "command": "npx",
      "args": [
        "-y",
        "@three-ws/x402-mcp"
      ],
      "env": {
        "SOLANA_SECRET_KEY": "your-value"
      }
    }
  }
}
```

Settings > Developer > Edit Config. macOS: ~/Library/Application Support/Claude/, Windows: %APPDATA%\Claude\. Restart Claude Desktop afterwards.

### Claude Code

```sh
claude mcp add --env SOLANA_SECRET_KEY=your-value --transport stdio x402-wallet -- npx -y @three-ws/x402-mcp
```

### Cursor (.cursor/mcp.json)

```json
{
  "mcpServers": {
    "x402-wallet": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "@three-ws/x402-mcp"
      ],
      "env": {
        "SOLANA_SECRET_KEY": "your-value"
      }
    }
  }
}
```

Project file; use ~/.cursor/mcp.json to enable it in every project.

### VS Code (.vscode/mcp.json)

```json
{
  "inputs": [
    {
      "type": "promptString",
      "id": "solana_secret_key",
      "description": "SOLANA_SECRET_KEY",
      "password": true
    }
  ],
  "servers": {
    "x402-wallet": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "@three-ws/x402-mcp"
      ],
      "env": {
        "SOLANA_SECRET_KEY": "${input:solana_secret_key}"
      }
    }
  }
}
```

Config formats checked against the official docs on 2026-10-07.

## Environment variables

- `SOLANA_SECRET_KEY` (secret): Base58 (or JSON byte-array) Solana secret key that signs payments and holds the USDC. Not needed for the read tools (findservices, inspectendpoint, or…
- `SOLANA_RPC_URL`: Solana mainnet RPC endpoint. Defaults to the public cluster — bring your own (Helius / Quicknode / Triton) for production traffic.
- `MAX_PAY_USD`: Max USD a single payandcall may spend. Bounds a runaway or injected payment.
- `REQUIRE_CONFIRM`: When on (default), payandcall refuses until re-issued with confirm:true. Set 0/false to disable the gate.
- `THREE_WS_BASE`: Base URL of the three.ws API that serves /api/bazaar/search for find_services. Override only when self-hosting.

## Tools

- `x402_wallet`: read-only
- `find_services`: read-only
- `inspect_endpoint`: read-only
- `pay_and_call`: execution
- `spending_report`: read-only
- `weather_forecast`: $0.001
- `weather_go_no_go`: $0.002
- `carbon_now`: $0.001
- `carbon_best_window`: $0.002
- `domain_rdap_check`: $0.001
- `domain_rdap_check_bulk`: $0.005
- `research_search`: $0.002
- `research_paper`: $0.003
- `research_bibliography`: $0.005
- `book_search`: $0.001
- `book_read`: $0.01
- `news_wire_search`: $0.003
- `news_wire_poll`: $0.002
- `transit_plan`: $0.002
- `transit_delays`: $0.001
- `places_search`: $0.002
- `places_detail`: $0.002

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