buy_stock

THE RISK

Critical Risk

Why buy_stock needs a policy

The tool name 'buy_stock' strongly implies it places a stock purchase order. Even though the server is described as 'paper trading' (simulated), it commits financial obligations within the trading system and uses real market data. Sibling tools confirm this is part of an order execution suite. The description is empty, so confidence is slightly reduced, but the context makes the classification clear.

From the tool's definition Tool name 'buy_stock' on a server with sibling tools like 'buy_stock_limit', 'buy_stock_stop', 'buy_option_limit', and description mentioning 'paper trading stocks' and 'real market data'

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

POLICY

How to control buy_stock

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_stock:

policy.json

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

Any call to buy_stock 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.

GATE THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Open Paper Trading MCP tools

Financial buy_option_limit Place a limit buy order for an option 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 →

Financial tools on other servers

0xarchive web3_subscribe Math MCP Server financial_calculator MCP Kling generate_video MCP Uber Server uber_request_ride

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_stock

What does the buy_stock tool do? +

buy_stock. 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_stock? +

Register the Open Paper Trading MCP server in PolicyLayer and add a rule for buy_stock: 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_stock? +

buy_stock 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_stock? +

Yes. Add a rate_limit block to the buy_stock 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_stock completely? +

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

buy_stock 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 →