AI agents call open_stock_orders to retrieve information from Open Paper Trading MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool only retrieves/queries existing open stock orders with no side effects. Despite being in a financial trading context, this is purely a read operation that returns data without modifying any state or committing any transactions.
From the tool's definition Retrieve all open stock orders
Documented attack patterns abuse exactly the kind of access open_stock_orders gives an agent:
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 open_stock_orders:
{
"version": "1",
"default": "deny",
"tools": {
"open_stock_orders": {}
}
} open_stock_orders is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Retrieve all open stock orders. It is categorised as a Read tool in the Open Paper Trading MCP MCP Server, which means it retrieves data without modifying state.
Register the Open Paper Trading MCP server in PolicyLayer and add a rule for open_stock_orders: 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.
open_stock_orders is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the open_stock_orders 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 open_stock_orders. 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.
open_stock_orders 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.
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.
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44 Open Paper Trading MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.