AI agents call list_trim to permanently remove resources in Prometheus MCP Server — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
Trimming a list to a range discards all elements outside that range. This is a destructive operation because the removed elements cannot be recovered. However, the context is Prometheus/AWS metrics which may be read-only queries; the description is sparse and the exact target data store is unclear, slightly lowering confidence.
From the tool's definition 'Trim list to specified range' — trimming a list removes elements outside the specified range, which is typically an irreversible destructive operation on the data structure.
Documented attack patterns abuse exactly the kind of access list_trim gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Prometheus MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for list_trim:
{
"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.
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Trim list to specified range. It is categorised as a Destructive tool in the Prometheus MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Prometheus MCP Server 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 Prometheus MCP Server. Nothing to install.
list_trim 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_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.
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.
list_trim is provided by the Prometheus MCP Server MCP server (awslabs.prometheus-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Prometheus MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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805 Prometheus MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.