cancel_order

THE RISK

Critical Risk

Why cancel_order needs a policy

Cancelling a financial order is irreversible — once cancelled, the order cannot be reinstated. This permanently terminates a trading intent and could have significant financial consequences if an agent mistakenly cancels legitimate orders.

From the tool's definition Cancel an open order by its ID

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

POLICY

How to control cancel_order

PolicyLayer is an MCP gateway — it sits between your AI agents and Alpaca Trading MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for cancel_order:

policy.json

{
  "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.

Create a free account and register Alpaca Trading MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RESTRICT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Alpaca Trading MCP Server tools

Financial place_stop_limit_order place_stop_limit_order Financial place_stop_order place_stop_order Financial place_limit_order place_limit_order Financial place_market_order Place a market order to buy or sell a stock. Financial close_position Close an open position for a specific symbol. Read get_account_info_tool Get current account information. Read get_portfolio_summary Get a comprehensive summary of the portfolio including account details and open positions.

All 8 Alpaca Trading MCP Server tools →

Destructive tools on other servers

Android Forensics ADB MCP Server create_full_backup 0xarchive web3_revoke_key Frida Game Hacking MCP clear_scan cPanel MCP Server clear_spam_box

Go deeper

Critical-risk tools in Alpaca Trading MCP Server → 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.
Blast radius → How much damage one compromised or confused agent can do — and how to bound it.
Tool call approval → Approval gates on individual tool calls: auto-allow, prompt, or deny.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about cancel_order

What does the cancel_order tool do? +

Cancel an open order by its ID. It is categorised as a Destructive tool in the Alpaca Trading MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.

How do I enforce a policy on cancel_order? +

Register the Alpaca Trading 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 Alpaca Trading MCP Server. Nothing to install.

What risk level is cancel_order? +

cancel_order is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit cancel_order? +

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.

How do I block cancel_order completely? +

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.

What MCP server provides cancel_order? +

cancel_order is provided by the Alpaca Trading MCP Server MCP server (laukikk/alpaca-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Alpaca Trading MCP Server tool call.

Start from Alpaca Trading MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →