Critical Risk →

buy_option_limit

Places a limit buy order for an option.

How to control buy_option_limit ↓

What buy_option_limit does on Open Stocks MCP

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

Critical Risk

Why buy_option_limit needs a policy

This tool directly executes a financial transaction — purchasing an options contract — which commits real capital and creates binding financial obligations. Options trading carries significant financial risk including potential loss of the entire premium paid or more. Misuse by an AI agent could result in substantial, potentially irreversible financial losses.

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

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

How to control buy_option_limit

PolicyLayer is an MCP gateway — it sits between your AI agents and Open Stocks 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.

  1. Create a free account and register Open Stocks MCP — nothing to install.
  2. Add this policy — paste it, or build it visually.
  3. Point your MCP client (Claude, Cursor, anything) at your gateway URL.
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Related tools and policies

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Questions about buy_option_limit

What does the buy_option_limit tool do? +

Places a limit buy order for an option. It is categorised as a Financial tool in the Open Stocks 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 Stocks 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 Stocks 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 Stocks MCP server (open-agent-tools/open-stocks-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 Stocks MCP tool call.

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

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152 Open Stocks MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.

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