# tunable_create

Create a new system tunable. Tunables allow setting sysctl, loader, or rc variables.

Agent View of the PolicyLayer registry record for `tunable_create`. HTML page: https://policylayer.com/tools/spranab-truenas-mcp/tunable-create

## Facts

- Tool: `tunable_create`
- Server: Truenas (`spranab/truenas-mcp`) — https://policylayer.com/tools/spranab-truenas-mcp.md
- Homepage: https://github.com/spranab/truenas-mcp
- Risk category: Write (Medium risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Rate-limited

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "tunable_create",
    "arguments": {}
  }
}
```

## Why tunable_create is rated Medium

This tool creates new system-level configuration parameters (sysctl, loader, rc variables) that modify kernel and system behavior. While reversible through deletion or reconfiguration, it modifies critical system settings that could affect system stability, performance, security posture, or service behavior. The high severity reflects that misconfiguration could destabilize the NAS or compromise security.

From the tool's own definition: "Create a new system tunable. Tunables allow setting sysctl, loader, or rc variables."

## Use case

AI agents use tunable_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.

## Recommended policy (PolicyLayer)

Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Truenas:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "tunable_create": {
      "limits": [
        {
          "counter": "tunable_create_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Truenas (278)

- `acme_dns_authenticator_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/acme-dns-authenticator-delete.md
- `alertservice_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/alertservice-delete.md
- `api_key_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/api-key-delete.md
- `app_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/app-delete.md
- `app_rollback` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/app-rollback.md
- `boot_attach_disk` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/boot-attach-disk.md
- `boot_detach_disk` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/boot-detach-disk.md
- `bootenv_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/bootenv-delete.md
- `certificate_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/certificate-delete.md
- `cloud_backup_abort` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/cloud-backup-abort.md
- `cloud_backup_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/cloud-backup-delete.md
- `cloudsync_credentials_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/cloudsync-credentials-delete.md
- `cloudsync_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/cloudsync-delete.md
- `cronjob_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/cronjob-delete.md
- `dataset_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/dataset-delete.md
- `directory_services_leave` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/directory-services-leave.md
- `disk_wipe` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/disk-wipe.md
- `group_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/group-delete.md
- `initshutdown_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/initshutdown-delete.md
- `iscsi_extent_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/iscsi-extent-delete.md
- `iscsi_initiator_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/iscsi-initiator-delete.md
- `iscsi_portal_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/iscsi-portal-delete.md
- `iscsi_target_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/iscsi-target-delete.md
- `iscsi_targetextent_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/iscsi-targetextent-delete.md
- `keychaincredential_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/keychaincredential-delete.md
- `network_interface_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/network-interface-delete.md
- `network_rollback_changes` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/network-rollback-changes.md
- `network_static_route_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/network-static-route-delete.md
- `nfs_share_delete` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/nfs-share-delete.md
- `pool_export` — Destructive — https://policylayer.com/tools/spranab-truenas-mcp/pool-export.md
- …and 248 more: https://policylayer.com/tools/spranab-truenas-mcp.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=spranab-truenas-mcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/spranab-truenas-mcp