buy_option_limit

THE RISK

Critical Risk

Why buy_option_limit needs a policy

This tool executes a financial transaction — placing a limit buy order for an options contract. Even though described as 'paper trading', the tool commits a simulated financial obligation and is part of a trading system with real market data.

From the tool's definition Place a limit buy order for an option

Documented attack patterns abuse exactly the kind of access buy_option_limit gives an agent:

POLICY

How to control buy_option_limit

PolicyLayer is an MCP gateway — it sits between your AI agents and Open Paper Trading MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for buy_option_limit:

policy.json

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

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

Create a free account and register Open Paper Trading MCP — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

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EXPLORE

Related tools and policies

More Open Paper Trading MCP tools

Financial buy_stock buy_stock Financial buy_stock_limit Place a limit buy order for stocks Financial option_credit_spread option_credit_spread Financial option_debit_spread option_debit_spread Financial sell_option_limit Place a limit sell order for an option Financial sell_stock sell_stock Financial sell_stock_limit Place a limit sell order for stocks Destructive cancel_all_option_orders_tool Cancel all open option orders

All 44 Open Paper Trading MCP tools →

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Go deeper

Critical-risk tools in Open Paper Trading MCP → Every critical-risk tool this server exposes, in one view.
All critical-risk MCP tools → Every critical-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Human-in-the-loop → When a tool call should wait for a person — and when policy can decide alone.
Tool call approval → Approval gates on individual tool calls: auto-allow, prompt, or deny.
How to Add Spending Controls to Any MCP Agent →
Rate Limiting MCP Tool Calls: A Practical Guide →

FAQ

Questions about buy_option_limit

What does the buy_option_limit tool do? +

Place a limit buy order for an option. It is categorised as a Financial tool in the Open Paper Trading MCP MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on buy_option_limit? +

Register the Open Paper Trading MCP server in PolicyLayer and add a rule for buy_option_limit: 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 Open Paper Trading MCP. Nothing to install.

What risk level is buy_option_limit? +

buy_option_limit 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 buy_option_limit? +

Yes. Add a rate_limit block to the buy_option_limit 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 buy_option_limit completely? +

Set action: deny in the PolicyLayer policy for buy_option_limit. 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 buy_option_limit? +

buy_option_limit is provided by the Open Paper Trading MCP server (open-agent-tools/open-paper-trading-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Open Paper Trading MCP tool call.

Start from Open Paper Trading MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →