AI agents call list_policies 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.
The 'list_policies' tool most likely queries and retrieves AWS policy objects for inspection or analysis. Listing policies does not modify, delete, or execute arbitrary operations—it is a read-only query operation with minimal blast radius. Confidence is slightly reduced due to missing tool description, but the naming convention and context strongly indicate a data retrieval function.
From the tool's definition Tool name 'list_policies' combined with sibling tools like 'aggregate', 'analyze_batch_translation_errors', and 'analyze_canary_failures' (all query/analytics operations) suggests this retrieves policy information.
Documented attack patterns abuse exactly the kind of access list_policies 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_policies:
{
"version": "1",
"default": "deny",
"tools": {
"list_policies": {}
}
}list_policies is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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list_policies. 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 list_policies: 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_policies 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 list_policies 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_policies. 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_policies 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.