back · Hermes Computer Use MCP: Risk & Policy

WHAT IT DOES

What back does on Hermes Computer Use

AI agents invoke back 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 back needs a policy

This tool executes a browser navigation action (going back in history) using OS-level keyboard simulation. It has side effects in the sense that it changes the browser state and navigation history, making it an Execute category action. The blast radius is low since it only navigates back one page.

From the tool's definition Browser back (alt+Left) — triggers a browser navigation action via OS-level keyboard input

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

back Rate-limited

back 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": {
    "back": {
      "limits": [
        {
          "counter": "back_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 back

What does the back tool do? +

Browser back (alt+Left). 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 back? +

Register the Hermes Computer Use MCP server in PolicyLayer and add a rule for back: 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 back? +

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

Can I rate-limit back? +

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

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

back 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.