left_click · Hermes Computer Use MCP: Risk & Policy

WHAT IT DOES

What left_click does on Hermes Computer Use

AI agents invoke left_click 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 left_click needs a policy

Clicking in a browser can trigger any action: form submissions, navigation, downloads, purchases, deletions. The effect is entirely argument-dependent and constitutes execution of external browser operations. Severity is high because in the context of a full browser automation suite evading anti-bot detection, a misused click could trigger irreversible or financial actions on arbitrary web pages.

From the tool's definition Move to (x,y) then single left-click — triggers OS-level mouse click actions in a real browser, driving UI interactions whose effects depend entirely on what element is clicked.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

left_click Rate-limited

left_click 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": {
    "left_click": {
      "limits": [
        {
          "counter": "left_click_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 left_click

What does the left_click tool do? +

Move to (x,y) then single left-click. 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 left_click? +

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

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

Can I rate-limit left_click? +

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

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

left_click 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.