AI agents call policy_list to retrieve information from Prometheus MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Policy listing is a non-destructive query operation that retrieves information about AWS Prometheus policies. Even though the description is empty, the naming convention indicates this retrieves or enumerates existing policies rather than creating, modifying, or deleting them. The confidence is moderate due to the missing description, but the clear 'list' semantics place this in the Read category with low severity.
From the tool's definition Tool name 'policy_list' indicates a listing/retrieval operation with no modification described. The empty description limits confidence, but the 'list' suffix strongly suggests a read operation that queries existing policies without side effects.
Documented attack patterns abuse exactly the kind of access policy_list 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 policy_list:
{
"version": "1",
"default": "deny",
"tools": {
"policy_list": {}
}
}policy_list is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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policy_list. It is categorised as a Read tool in the Prometheus MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Prometheus MCP Server MCP server in PolicyLayer and add a rule for policy_list: 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.
policy_list is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the policy_list 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 policy_list. 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.
policy_list 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.