Critical Risk →

snapshot_delete

Delete a ZFS snapshot (destructive — requires confirm)

How to control snapshot_delete ↓

What snapshot_delete does on Truenas

AI agents call snapshot_delete to permanently remove resources in Truenas — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.

Critical Risk

Why snapshot_delete needs a policy

The tool explicitly deletes a ZFS snapshot and is labeled as destructive. ZFS snapshots are point-in-time backups; deleting them is irreversible and can result in permanent loss of recovery points, making this a high-severity destructive action.

From the tool's definition Delete a ZFS snapshot (destructive — requires confirm)

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

How to control snapshot_delete

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 snapshot_delete:

policy.json
{
  "version": "1",
  "default": "deny",
  "hide": [
    "snapshot_delete"
  ]
}

snapshot_delete disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.

  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.
RESTRICT THIS TOOL →

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Related tools and policies

Go deeper

Questions about snapshot_delete

What does the snapshot_delete tool do? +

Delete a ZFS snapshot (destructive — requires confirm). It is categorised as a Destructive tool in the Truenas MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.

How do I enforce a policy on snapshot_delete? +

Register the Truenas MCP server in PolicyLayer and add a rule for snapshot_delete: 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 snapshot_delete? +

snapshot_delete is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit snapshot_delete? +

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

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

snapshot_delete 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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