place_limit_order · Alpaca MCP Server MCP: Risk & Policy

WHAT IT DOES

What place_limit_order does on Alpaca MCP Server

AI agents use place_limit_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_limit_order needs a policy

Placing a limit order directly commits a financial obligation to buy or sell securities at a specified price. Misuse by an AI agent could result in unintended trades with real monetary consequences, making this a critical financial risk.

From the tool's definition 'Place a limit order' on an Alpaca trading API server described as enabling 'trading stocks' and 'managing accounts'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

place_limit_order Approval-gated

Any call to place_limit_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_limit_order": {
      "deny_if": [
        {
          "conditions": [],
          "on_deny": "Requires human approval."
        }
      ]
    }
  }
}

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FAQ

Questions about place_limit_order

What does the place_limit_order tool do? +

Place a limit 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_limit_order? +

Register the Alpaca MCP Server MCP server in PolicyLayer and add a rule for place_limit_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_limit_order? +

place_limit_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_limit_order? +

Yes. Add a rate_limit block to the place_limit_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_limit_order completely? +

Set action: deny in the PolicyLayer policy for place_limit_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_limit_order? +

place_limit_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.