list_metric_descriptors

SERVERMcp SOURCEhttps://monitoring.googleapis.com/mcp

Low RISK CLASS

Category Read

Parameters 51 required

Recommended Allowedsee the rule below

Registry record Grade C, identity unverified Pull the record →

This record as markdown: /tools/com-googleapis-monitoring-mcp/list-metric-descriptors.md

WHAT IT DOES

What list_metric_descriptors does on Mcp

AI agents call list_metric_descriptors to retrieve information from Mcp without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

Parameter	Type	Required	Description
`name`	string	Yes	Required. The [project](https://cloud.google.com/monitoring/api/v3#project_name) on which to execute the request. The format is: projects/[PROJECT_ID_OR_NUMBER]
`filter`	string	—	Optional. If this field is empty, all custom and system-defined metric descriptors are returned. Otherwise, the [filter](https://cloud.google.com/monitoring/api
`pageSize`	integer	—	Optional. A positive number that is the maximum number of results to return. The default and maximum value is 10,000. If a page_size <= 0 or > 10,000 is submitt
`pageToken`	string	—	Optional. If this field is not empty then it must contain the `nextPageToken` value returned by a previous call to this method. Using this field causes the meth
`activeOnly`	boolean	—	Optional. If true, only metrics and monitored resource types that have recent data (within roughly 25 hours) will be included in the response. - If a metric des

Parameters from the server's own tool schema.

RISK

Why list_metric_descriptors is rated Low

This tool retrieves metadata about available metrics in a Google Cloud project. It performs a query operation to list metric descriptors without modifying data, executing code, or triggering external side effects. This is a straightforward read operation with minimal risk.

From the tool's definition Tool description states it is used to 'discover the types of metrics available' and 'understanding what data is available' — purely informational retrieval with no mutation or execution capability.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs list_metric_descriptors safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Mcp, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For list_metric_descriptors, this is the rule to start with:

list_metric_descriptors Allowed

list_metric_descriptors is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "list_metric_descriptors": {}
  }
}

ALLOW ONLY THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Mcp, apply this rule, and every list_metric_descriptors call is checked against it from then on.

FAQ

Questions about list_metric_descriptors

What does the list_metric_descriptors tool do? +

Use this as the primary tool to discover the types of metrics available in a Google Cloud project. This is a good first step to understanding what data is available for monitoring and building dashboards or alerts. It is categorised as a Read tool in the Mcp MCP Server, which means it retrieves data without modifying state.

What parameters does list_metric_descriptors accept? +

list_metric_descriptors accepts 5 parameters: name, filter, pageSize, pageToken, activeOnly. Required: name. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on list_metric_descriptors? +

Register the MCP server in PolicyLayer and add a rule for list_metric_descriptors: 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 Mcp. Nothing to install.

What risk level is list_metric_descriptors? +

list_metric_descriptors is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit list_metric_descriptors? +

Yes. Add a rate_limit block to the list_metric_descriptors 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.

How do I block list_metric_descriptors completely? +

Set action: deny in the PolicyLayer policy for list_metric_descriptors. 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.

What MCP server provides list_metric_descriptors? +

list_metric_descriptors is provided by the MCP server (https://monitoring.googleapis.com/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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