buy_stock_market

THE RISK

Critical Risk

Why buy_stock_market needs a policy

This tool directly executes a financial transaction by placing a real buy order through broker APIs (Robinhood/Schwab). A misuse or unintended invocation could result in immediate, potentially irreversible financial commitments at market price, making it critical severity under the Financial category.

From the tool's definition Places a market buy order for a stock

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

POLICY

How to control buy_stock_market

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_stock_market:

policy.json

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

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

Create a free account and register Open Stocks 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 Stocks MCP tools

Financial schwab_order_sell_stop Place a stop sell order for stock. Financial sell_stock_stop_loss Places a stop loss sell order for a stock. Financial buy_option_limit Places a limit buy order for an option. Financial buy_stock_limit Places a limit buy order for a stock. Financial option_credit_spread option_credit_spread Financial option_debit_spread option_debit_spread Financial schwab_buy_stock_limit Place a limit buy order for stock. Financial schwab_buy_stock_market Place a market buy order for stock.

All 152 Open Stocks MCP tools →

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Go deeper

Critical-risk tools in Open Stocks 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_market

What does the buy_stock_market tool do? +

Places a market buy order for a stock. 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_stock_market? +

Register the Open Stocks MCP server in PolicyLayer and add a rule for buy_stock_market: 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_stock_market? +

buy_stock_market 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_market? +

Yes. Add a rate_limit block to the buy_stock_market 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_market completely? +

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

buy_stock_market 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.

CHECK YOUR STACK →