AI agents call gateway_target_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.
Based on naming convention, this appears to be a list/query operation typical of AWS resource inspection tools in Prometheus monitoring contexts. List operations are Read-category tools with minimal blast radius. The empty description and unfamiliar tool name prevent higher confidence, but the 'list' suffix strongly indicates a retrieval operation rather than modification, deletion, or execution.
From the tool's definition The tool name 'gateway_target_list' suggests it retrieves or lists gateway targets, consistent with Read operations that query data without side effects. No description provided to confirm, lowering confidence.
Documented attack patterns abuse exactly the kind of access gateway_target_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 gateway_target_list:
{
"version": "1",
"default": "deny",
"tools": {
"gateway_target_list": {}
}
}gateway_target_list is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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gateway_target_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 gateway_target_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.
gateway_target_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 gateway_target_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 gateway_target_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.
gateway_target_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.