attach_volume · Hcloud MCP: Risk & Policy

WHAT IT DOES

What attach_volume does on Hcloud

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

WHY IT NEEDS A POLICY

Why attach_volume needs a policy

Attaching a volume to a server modifies infrastructure state but is not destructive (can be detached). It is not Execute because it does not run code or arbitrary commands — the attachment itself is a discrete cloud API operation.

From the tool's definition Tool name is 'attach_volume' and description states 'Attach a volume to a server' — this modifies server configuration by attaching persistent storage, a reversible action.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

attach_volume Rate-limited

attach_volume 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": {
    "attach_volume": {
      "limits": [
        {
          "counter": "attach_volume_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Hcloud, so you can run agents against it safely.

FAQ

Questions about attach_volume

What does the attach_volume tool do? +

Attach a volume to a server. It is categorised as a Write tool in the Hcloud MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on attach_volume? +

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

What risk level is attach_volume? +

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

Can I rate-limit attach_volume? +

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

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

attach_volume is provided by the Hcloud MCP server (xodus-co/hcloud-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.