AI agents call get_metric_metadata 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 name suggests this tool retrieves or queries metric metadata from AWS Managed Prometheus without modifying or executing actions. This is a Read operation. Severity is low because metadata retrieval has minimal blast radius—it exposes information about available metrics but does not execute queries, modify data, or trigger external operations.
From the tool's definition Tool name 'get_metric_metadata' indicates retrieval of metadata about metrics from Prometheus; 'get' prefix is characteristic of query operations that do not modify state.
Documented attack patterns abuse exactly the kind of access get_metric_metadata 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 get_metric_metadata:
{
"version": "1",
"default": "deny",
"tools": {
"get_metric_metadata": {}
}
}get_metric_metadata is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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get_metric_metadata. 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 get_metric_metadata: 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.
get_metric_metadata 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 get_metric_metadata 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 get_metric_metadata. 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.
get_metric_metadata 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.