AI agents call cancel_order to permanently remove resources in Paper MCP Server — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
Canceling a trading order is a destructive financial action that cannot be undone. While related to financial operations, the defining characteristic here is irreversibility: a canceled order cannot be restored. This makes it Destructive rather than Financial.
From the tool's definition Tool name 'cancel_order' combined with server description indicating it 'interact[s] with Paper's trading platform API' and allows users to 'manage accounts, portfolios, trades'.
Documented attack patterns abuse exactly the kind of access cancel_order gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Paper MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for cancel_order:
{
"version": "1",
"default": "deny",
"hide": [
"cancel_order"
]
}cancel_order disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.
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Cancel an existing order. It is categorised as a Destructive tool in the Paper MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Paper MCP Server MCP server in PolicyLayer and add a rule for cancel_order: 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 Paper MCP Server. Nothing to install.
cancel_order is a Destructive 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 cancel_order 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 cancel_order. 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.
cancel_order is provided by the Paper MCP Server MCP server (paperinvest/mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Paper MCP Server, 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.
23 Paper MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.