Medium Risk

vm_create

Create a new virtual machine. At minimum provide a name and memory (in MiB). Other fields have sensible defaults.

How to control vm_create ↓

What vm_create does on Truenas

AI agents use vm_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.

Medium Risk

Why vm_create needs a policy

This tool creates a new VM resource on TrueNAS SCALE. It is a Write operation (creates a new entity reversibly — the VM can be deleted afterward). The severity is high because creating VMs consumes significant system resources (memory, storage, CPU) and could be misused to exhaust system capacity or deploy unauthorized workloads.

From the tool's definition Create a new virtual machine. At minimum provide a name and memory (in MiB).

Documented attack patterns abuse exactly the kind of access vm_create gives an agent:

How to control vm_create

PolicyLayer is an MCP gateway — it sits between your AI agents and Truenas, and nothing reaches the server without passing your rules. This is the rule we recommend for vm_create:

policy.json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "vm_create": {
      "limits": [
        {
          "counter": "vm_create_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

vm_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.

  1. Create a free account and register Truenas — nothing to install.
  2. Add this policy — paste it, or build it visually.
  3. Point your MCP client (Claude, Cursor, anything) at your gateway URL.
LIMIT THIS TOOL →

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Related tools and policies

Go deeper

Questions about vm_create

What does the vm_create tool do? +

Create a new virtual machine. At minimum provide a name and memory (in MiB). Other fields have sensible defaults. 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_create? +

Register the Truenas MCP server in PolicyLayer and add a rule for vm_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_create? +

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

Can I rate-limit vm_create? +

Yes. Add a rate_limit block to the vm_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_create completely? +

Set action: deny in the PolicyLayer policy for vm_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_create? +

vm_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.

Enforce policy on every Truenas tool call.

Start from Truenas, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

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279 Truenas tools catalogued and risk-classified — across an index of 43,000+ MCP servers.

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