Get all values for a specific label from a Prometheus datasource
AI agents call get_prometheus_label_values to retrieve information from Grafana MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries Prometheus to retrieve label values—a read-only operation that has no side effects, does not execute arbitrary code, and does not modify or delete data. The blast radius of misuse is minimal; an agent could only enumerate metrics metadata, which is typically non-sensitive operational information. It falls squarely into the Read category.
From the tool's definition Tool name 'get_prometheus_label_values' and description 'Get all values for a specific label from a Prometheus datasource' indicate a retrieval operation with no data modification or execution capability.
Attacks that exploit this kind of access
Get all values for a specific label from a Prometheus datasource. It is categorised as a Read tool in the Grafana MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Grafana MCP Server MCP server in PolicyLayer and add a rule for get_prometheus_label_values: 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 Grafana MCP Server. Nothing to install.
get_prometheus_label_values 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_prometheus_label_values 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_prometheus_label_values. 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_prometheus_label_values is provided by the Grafana MCP Server MCP server (quanticsoul4772/grafana-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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