vm_device_create

Create a new device and attach it to a VM. The

SERVERTruenas SOURCEspranab/truenas-mcp

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/spranab-truenas-mcp/vm-device-create.md

WHAT IT DOES

What vm_device_create does on Truenas

AI agents use vm_device_create to create or update resources in Truenas, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Truenas environment.

RISK

Why vm_device_create is rated Medium

This tool creates a new VM device and attaches it to an existing virtual machine. While this modifies system configuration and VM state, it is reversible (the device can be detached and removed), so it falls into Write rather than Destructive.

From the tool's definition Tool name is 'vm_device_create' and description states 'Create a new device and attach it to a VM.' The verbs 'create' and 'attach' indicate data modification operations.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs vm_device_create safely

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

vm_device_create Rate-limited

vm_device_create stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "vm_device_create": {
      "limits": [
        {
          "counter": "vm_device_create_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

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

FAQ

Questions about vm_device_create

What does the vm_device_create tool do? +

Create a new device and attach it to a VM. The. It is categorised as a Write tool in the Truenas MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on vm_device_create? +

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

What risk level is vm_device_create? +

vm_device_create is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit vm_device_create? +

Yes. Add a rate_limit block to the vm_device_create 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 vm_device_create completely? +

Set action: deny in the PolicyLayer policy for vm_device_create. 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 vm_device_create? +

vm_device_create is provided by the Truenas MCP server (spranab/truenas-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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