list_instances
Lists Compute Engine virtual machine (VM) instances. Details for each instance include name, ID, status, machine type, creation timestamp, and attached guest accelerators. Use other tools to get more details about each instance. Requires project and zone as input.
This record as markdown: /tools/com-googleapis-compute-mcp/list-instances.md
What list_instances does on Mcp
AI agents call list_instances 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 |
|---|---|---|---|
zone | string | Yes | Required. The zone of the instances. |
project | string | Yes | Required. Project ID for this request. |
pageSize | integer | — | Optional. The maximum number of instances to return. |
pageToken | string | — | Optional. A page token received from a previous call to list instances. |
Parameters from the server's own tool schema.
Why list_instances is rated Low
This tool queries and retrieves infrastructure information without creating, modifying, deleting, or executing any operations. It is a read-only operation with minimal security impact, as it merely enumerates existing resources and their basic properties. The blast radius is low since it only provides informational data.
From the tool's definition Tool description states it 'Lists Compute Engine virtual machine (VM) instances' and returns 'name, ID, status, machine type, creation timestamp, and attached guest accelerators' — purely retrieval of metadata with no modification or execution capability.
Attacks that exploit this kind of access
The rule that runs list_instances 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_instances, this is the rule to start with:
list_instances is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Mcp, apply this rule, and every list_instances call is checked against it from then on.
Questions about list_instances
Lists Compute Engine virtual machine (VM) instances. Details for each instance include name, ID, status, machine type, creation timestamp, and attached guest accelerators. Use other tools to get more details about each instance. Requires project and zone as input. It is categorised as a Read tool in the Mcp MCP Server, which means it retrieves data without modifying state.
list_instances accepts 4 parameters: zone, project, pageSize, pageToken. Required: zone, project. The full parameter table on this page comes from the server's own tool schema.
Register the MCP server in PolicyLayer and add a rule for list_instances: 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.
list_instances 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 list_instances 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 list_instances. 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.
list_instances is provided by the MCP server (https://compute.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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