browser_emulate · Wmux MCP: Risk & Policy

WHAT IT DOES

What browser_emulate does on Wmux

AI agents invoke browser_emulate to trigger actions in Wmux. 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 browser_emulate needs a policy

This tool triggers external operations whose effects depend on arguments—it modifies browser state and potentially affects how web pages respond. While not destructive or financial, it constitutes active execution of browser-level operations.

From the tool's definition Tool applies emulation settings to browser pages including 'offline mode, custom headers, HTTP credentials, geolocation, color scheme, timezone, locale, or device preset.' These are runtime modifications that alter browser behavior and external system state…

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

browser_emulate Rate-limited

browser_emulate 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": {
    "browser_emulate": {
      "limits": [
        {
          "counter": "browser_emulate_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 Wmux, so you can run agents against it safely.

FAQ

Questions about browser_emulate

What does the browser_emulate tool do? +

Apply emulation settings to the browser page: offline mode, custom headers, HTTP credentials, geolocation, color scheme, timezone, locale, or device preset. It is categorised as a Execute tool in the Wmux MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on browser_emulate? +

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

What risk level is browser_emulate? +

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

Can I rate-limit browser_emulate? +

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

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

browser_emulate is provided by the Wmux MCP server (openwong2kim/wmux). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.