Pop value(s) from right of list. Args: key: The name of the key count: Number of values to pop (optional) Returns: Value(s) or error message
AI agents use list_pop_right to create or update resources in AWS — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your AWS environment.
Popping from a list is a destructive modification (removes data), but the data is returned to the caller, making it partially reversible if the caller retains the value. It modifies state but is not a permanent/irreversible deletion in the classical sense, so Write is the most appropriate category over Destructive. Misuse could cause data loss if the popped values are discarded.
From the tool's definition Pop value(s) from right of list — 'pop' removes and returns elements, modifying the list in place
Documented attack patterns abuse exactly the kind of access list_pop_right gives an agent:
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_pop_right:
{
"version": "1",
"default": "deny",
"tools": {
"list_pop_right": {
"limits": [
{
"counter": "list_pop_right_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}list_pop_right stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Pop value(s) from right 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 Write tool in the AWS MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the AWS MCP server in PolicyLayer and add a rule for list_pop_right: 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_right is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the list_pop_right 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_right. 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_right 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.
Start from AWS, 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.
300 AWS tools catalogued and risk-classified — across an index of 43,000+ MCP servers.