Critical Risk →

list_trim

Trim list to specified range. Args: key: The name of the key start: Start index (inclusive) stop: Stop index (inclusive) Returns: Success message or error message

How to control list_trim ↓

What list_trim does on AWS

AI agents call list_trim to permanently remove resources in AWS — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.

Critical Risk

Why list_trim needs a policy

LTRIM (Redis list trim) removes all elements outside the specified start/stop range. This is an irreversible deletion of data; elements outside the range are discarded and cannot be recovered without a backup. This qualifies as Destructive rather than Write because the removal of data is not easily reversible.

From the tool's definition "Trim list to specified range" — elements outside the specified range are permanently removed from the list

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

How to control list_trim

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

policy.json
{
  "version": "1",
  "default": "deny",
  "hide": [
    "list_trim"
  ]
}

list_trim disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.

  1. Create a free account and register AWS — nothing to install.
  2. Add this policy — paste it, or build it visually.
  3. Point your MCP client (Claude, Cursor, anything) at your gateway URL.
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Related tools and policies

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Questions about list_trim

What does the list_trim tool do? +

Trim list to specified range. Args: key: The name of the key start: Start index (inclusive) stop: Stop index (inclusive) Returns: Success message or error message. It is categorised as a Destructive tool in the AWS 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 list_trim? +

Register the AWS MCP server in PolicyLayer and add a rule for list_trim: 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 AWS. Nothing to install.

What risk level is list_trim? +

list_trim 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 list_trim? +

Yes. Add a rate_limit block to the list_trim 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 list_trim completely? +

Set action: deny in the PolicyLayer policy for list_trim. 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 list_trim? +

list_trim is provided by the AWS MCP server (@awslabs/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every AWS tool call.

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

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300 AWS tools catalogued and risk-classified — across an index of 43,000+ MCP servers.

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