AI agents call list_pop_left to permanently remove resources in Document Loader MCP Server — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
Popping an element removes it from the list permanently. This constitutes an irreversible data modification/deletion, placing it in the Destructive category. Severity is medium as it affects list data elements. Confidence is moderate because the description is brief and context about what list or data store is being modified is missing, making it unclear about the full blast radius.
From the tool's definition 'Pop value(s) from left of list' — popping removes elements from the data structure, which is an irreversible deletion of those values from the list.
Documented attack patterns abuse exactly the kind of access list_pop_left gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Document Loader MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for list_pop_left:
{
"version": "1",
"default": "deny",
"hide": [
"list_pop_left"
]
}list_pop_left 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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Pop value(s) from left of list. It is categorised as a Destructive tool in the Document Loader MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Document Loader MCP Server 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 Document Loader MCP Server. 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 Document Loader MCP Server MCP server (awslabs.document-loader-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Document Loader 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.
805 Document Loader MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.