undo · Hermes Computer Use MCP: Risk & Policy

WHAT IT DOES

What undo does on Hermes Computer Use

AI agents invoke undo to trigger actions in Hermes Computer Use. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why undo needs a policy

This tool triggers an OS-level keyboard action (Ctrl+Z) in a real browser, which executes a command that modifies the state of a UI widget by reverting its last edit. While it superficially reverses a change, it is an active browser/OS operation with side effects dependent on the current context—fitting the Execute category. It could inadvertently restore sensitive or unintended content in the focused element.

From the tool's definition Undo the last edit in the focused widget (ctrl+z)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

undo Rate-limited

undo stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "undo": {
      "limits": [
        {
          "counter": "undo_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about undo

What does the undo tool do? +

Undo the last edit in the focused widget (ctrl+z). It is categorised as a Execute tool in the Hermes Computer Use MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on undo? +

Register the Hermes Computer Use MCP server in PolicyLayer and add a rule for undo: 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 Hermes Computer Use. Nothing to install.

What risk level is undo? +

undo is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit undo? +

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

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

undo is provided by the Hermes Computer Use MCP server (noah3521/hermes-computer-use). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.