This record as markdown: /tools/aws/list-pop-left.md
What list_pop_left does on AWS
AI agents call list_pop_left 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.
Why list_pop_left is rated Critical
Popping values from a list removes them permanently from the data store. This is a destructive operation because the data is consumed/deleted from the list and cannot be recovered without a separate backup. While it may seem like a minor operation, misuse by an AI agent could lead to unintended data loss from Redis or similar list-based storage.
From the tool's definition Pop value(s) from left of list — 'pop' removes elements from the data structure irreversibly
Attacks that exploit this kind of access
The rule that runs list_pop_left safely
PolicyLayer is an MCP gateway: it sits between your AI agents and AWS, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For list_pop_left, this is the rule to start with:
list_pop_left is removed from the agent's tool list entirely, so the agent never calls it. The rest of the server keeps working.
The button opens the PolicyLayer dashboard: create your workspace, connect AWS, apply this rule, and every list_pop_left call is checked against it from then on.
Questions about list_pop_left
Pop value(s) from left of list. Args: key: The name of the key count: Number of values to pop (optional) Returns: Value(s) 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.
Register the AWS MCP server in PolicyLayer and add a rule for list_pop_left: 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.
list_pop_left 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 list_pop_left 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 list_pop_left. 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.
list_pop_left 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.
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