TAS Guard MCP server

TAS Guard

A trading-aware safety proxy for AI agents. Put it between your AI client (Claude, ChatGPT, Cursor, your own agent) and any broker or exchange MCP server. It enforces per-order and daily limits, symbol allowlists, human approvals, a kill switch and a tamper-evident audit log, before an order ever reaches your broker.

AI client  ──►  TAS Guard  ──►  Alpaca / CCXT / any trading MCP server  ──►  your account
                   │
                   ├─ blocks: over-limit orders, off-list symbols, withdrawals, leverage changes
                   ├─ asks you: large orders, live money, "close everything"
                   └─ logs: every decision, hash-chained

Zero dependencies. About 2,000 lines of plain JavaScript you can read in one sitting.

New in 0.3: onchain (EVM) mode. The same limits, approvals, kill switch and audit log for agents that hold their own wallet: tas-guard rpc is a local JSON-RPC endpoint your agent uses as its RPC URL.

Try it in 10 seconds (no broker account)

tas-guard demo runs the guard in front of a built-in paper broker with simulated prices. Add it to your AI app as an MCP server:

{ "mcpServers": { "tas-guard-demo": { "command": "npx", "args": ["-y", "tas-guard", "demo"] } } }

(On Windows use "command": "cmd", "args": ["/c", "npx", "-y", "tas-guard", "demo"].) Then ask your agent to buy 1 SPY at $580 (allowed), 2 SPY at $580 (held for your approval), 10 SPY (blocked: over the $2,000 per-order limit) or 1 TSLA (blocked: not on the allow list). Approve held orders with npx tas-guard approve .

Why not a generic MCP gateway?

Generic gateways decide per tool: "createOrder is critical, require approval." They can't tell a $50 order from a $50,000 one, so you end up approving everything or nothing.

TAS Guard reads the order itself. It knows that Alpaca's placeoptionorder has a 100x contract multiplier, that ccxt's cost is a quote-currency value while amount is base units, and that ccxt answers the first live order with a preview. That's what makes "allow small orders, ask for big ones, never exceed $2,000 a day" possible.

Safety scores and order-gating facts: tradingagentstack.com.

Quick start (Alpaca, paper trading)

1. Write ~/tas-guard/alpaca.json (or run npx tas-guard init alpaca-mcp-server):

{
  "name": "alpaca",
  "profile": "alpaca-mcp-server",
  "upstream": {
    "command": "uvx",
    "args": ["alpaca-mcp-server"],
    "env": {
      "ALPACA_API_KEY": "${ALPACA_API_KEY}",
      "ALPACA_SECRET_KEY": "${ALPACA_SECRET_KEY}",
      "ALPACA_PAPER_TRADE": "true"
    }
  },
  "policy": {
    "max_order_value": 500,
    "max_daily_value": 2000,
    "approve_over": 250,
    "symbols_allow": ["SPY", "QQQ", "AAPL", "MSFT"]
  }
}

${VAR} is read from the environment, so keys don't have to live in the file.

1. Point your MCP client at the guard instead of at Alpaca. For Claude Desktop (claudedesktopconfig.json):

{
  "mcpServers": {
    "alpaca": {
      "command": "npx",
      "args": ["-y", "tas-guard", "run", "--config", "/Users/you/tas-guard/alpaca.json"],
      "env": { "ALPACA_API_KEY": "...", "ALPACA_SECRET_KEY": "..." }
    }
  }
}

For Claude Code: claude mcp add alpaca -- npx -y tas-guard run --config ~/tas-guard/alpaca.json

Shortened. The full README is on GitHub.