select_all · Hermes Computer Use MCP: Risk & Policy

WHAT IT DOES

What select_all does on Hermes Computer Use

AI agents invoke select_all 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 select_all needs a policy

This tool executes a keyboard shortcut (Ctrl+A) in a live browser session. While selecting text is nominally benign, it is an active browser automation action that interacts with real OS-level input and can be a step in a larger destructive or exfiltrating workflow (e.g., select-all then copy or delete). It is an Execute-class action due to triggering external browser/OS operations.

From the tool's definition Select all content in the focused widget (ctrl+a) — triggers OS-level keyboard action in a real browser

Risk signalsBulk/mass operation — affects multiple targets

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

select_all Rate-limited

select_all 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": {
    "select_all": {
      "limits": [
        {
          "counter": "select_all_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 select_all

What does the select_all tool do? +

Select all content in the focused widget (ctrl+a). 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 select_all? +

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

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

Can I rate-limit select_all? +

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

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

select_all 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.