AI agents use schwab_buy_stock_market to commit financial operations through Open Stocks MCP — usually the final step of a payment, billing, or trading workflow. A call moves real money.
This tool directly executes financial transactions by placing market buy orders for stocks through broker APIs (Robinhood/Schwab). It commits real financial obligations and moves money. Misuse could result in unintended large purchases, significant financial loss, or unauthorized trades — making it critical severity.
From the tool's definition Place a market buy order for stock
Documented attack patterns abuse exactly the kind of access schwab_buy_stock_market gives an agent:
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 schwab_buy_stock_market:
{
"version": "1",
"default": "deny",
"tools": {
"schwab_buy_stock_market": {
"deny_if": [
{
"conditions": [],
"on_deny": "Requires human approval."
}
]
}
}
} Any call to schwab_buy_stock_market is blocked until a human approves it. The rest of the server keeps working.
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Place a market buy order for 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.
Register the Open Stocks MCP server in PolicyLayer and add a rule for schwab_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.
schwab_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.
Yes. Add a rate_limit block to the schwab_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.
Set action: deny in the PolicyLayer policy for schwab_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.
schwab_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.
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.
Free to start. No card required.
152 Open Stocks MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.