AI agents use sell_stock_limit to commit financial operations through Open Paper Trading MCP — usually the final step of a payment, billing, or trading workflow. A call moves real money.
This tool places a sell order for stocks, which is a financial transaction. Although the server description states it's paper trading (simulated, no real financial risk), the tool itself commits financial obligations within the trading system. It fits the Financial category as it moves/commits assets in a trading context.
From the tool's definition 'sell_stock_limit' and 'Place a limit sell order for stocks'
Documented attack patterns abuse exactly the kind of access sell_stock_limit 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 sell_stock_limit:
{
"version": "1",
"default": "deny",
"tools": {
"sell_stock_limit": {
"deny_if": [
{
"conditions": [],
"on_deny": "Requires human approval."
}
]
}
}
} Any call to sell_stock_limit is blocked until a human approves it. The rest of the server keeps working.
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Place a limit sell order for stocks. 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.
Register the Open Paper Trading MCP server in PolicyLayer and add a rule for sell_stock_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 Paper Trading MCP. Nothing to install.
sell_stock_limit 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 sell_stock_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.
Set action: deny in the PolicyLayer policy for sell_stock_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.
sell_stock_limit 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.
Free to start. No card required.
44 Open Paper Trading MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.