place_market_order · Alpaca MCP Server MCP: Risk & Policy

WHAT IT DOES

What place_market_order does on Alpaca MCP Server

AI agents use place_market_order to commit financial operations through Alpaca MCP Server — usually the final step of a payment, billing, or trading workflow. A call moves real money.

WHY IT NEEDS A POLICY

Why place_market_order needs a policy

Placing a market order directly commits a financial transaction — buying or selling securities at current market prices. This is irreversible once executed and can result in significant financial exposure. It is the highest severity Financial action.

From the tool's definition 'Place a market order' on a server that enables 'trading stocks' via the Alpaca trading API

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

place_market_order Approval-gated

Any call to place_market_order is blocked until a human approves it. The rest of the server keeps working.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "place_market_order": {
      "deny_if": [
        {
          "conditions": [],
          "on_deny": "Requires human approval."
        }
      ]
    }
  }
}

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PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Alpaca MCP Server, so you can run agents against it safely.

FAQ

Questions about place_market_order

What does the place_market_order tool do? +

Place a market order. It is categorised as a Financial tool in the Alpaca MCP Server MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on place_market_order? +

Register the Alpaca MCP Server MCP server in PolicyLayer and add a rule for place_market_order: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Alpaca MCP Server. Nothing to install.

What risk level is place_market_order? +

place_market_order is a Financial tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit place_market_order? +

Yes. Add a rate_limit block to the place_market_order rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block place_market_order completely? +

Set action: deny in the PolicyLayer policy for place_market_order. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides place_market_order? +

place_market_order is provided by the Alpaca MCP Server MCP server (miguelyad26/alpaca-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.