Wallie MCP

A spending allowance for your MCP client. Point Claude Desktop, an agent framework — anything that speaks the Model Context Protocol — at wallie-mcp, and it pays any x402-priced API on its own, inside hard limits you set, with a kill switch and a receipt for every cent.

wallie-mcp serves allowance-kit's runtime over stdio. It binds one agent, resolved from the state directory exactly as the CLI resolves it: a fresh directory is practice money, a directory you have marked live (with AGENT_PRIVATE_KEY set) settles real USDC on Base or Solana.

export ALLOWANCE_STATE_DIR=.allowance   # optional, this is the default
npx [email protected]                    # speaks MCP over stdio

In a client config, e.g. claude_desktop_config.json:

{
  "mcpServers": {
    "wallie": { "command": "npx", "args": ["--yes", "[email protected]"], "env": { "ALLOWANCE_STATE_DIR": ".allowance" } }
  }
}

Five tools: pay_fetch, get_budget, list_channels, decide_approval, and reclaim_channel. pay_fetch chooses exact or upto per the seller's offer; a refused payment comes back as a blocked reason in plain language, never an exception.

The package includes the MCP SDK and the Base and Solana signing libraries, so a fresh npx installation can resolve the live runtime's optional peers. The core allowance-kit package keeps those peers optional for SDK users.

decide_approval is administrative authority. A client given this tool can approve its own queued requests. Only expose it to a trusted client; it is not a separate human authentication boundary. Spending that bypasses Wallie is outside its allowance controls.

The same surface is importable from the SDK:

import { createMcpServer, runMcpStdio } from "wallie-mcp"; // or from "allowance-kit/mcp"

Full documentation, the changelog, and the source live in the allowance-kit repository.