AI agents call gateway_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.
The tool name pattern 'gateway_list' indicates a query or enumeration operation that retrieves gateway information from AWS Managed Prometheus without modification. List operations are characteristically Read category with low severity since they retrieve data without side effects. Confidence is moderate rather than high due to the empty description, but the naming convention provides reasonable evidence.
From the tool's definition Tool name 'gateway_list' strongly suggests a listing/query operation typical of Read category tools. The description is empty, which prevents definitive confirmation, but the naming convention aligns with retrieval operations.
Documented attack patterns abuse exactly the kind of access gateway_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_list:
{
"version": "1",
"default": "deny",
"tools": {
"gateway_list": {}
}
}gateway_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_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_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_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_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_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_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.