browser_wait · Wmux MCP: Risk & Policy

WHAT IT DOES

What browser_wait does on Wmux

AI agents invoke browser_wait 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_wait needs a policy

This tool executes code (JavaScript predicates) and performs browser state monitoring, which are Execute-category operations. While waiting for a condition is passive, the ability to run custom JS predicates means code execution is involved.

From the tool's definition Tool description states it can evaluate 'custom JS predicate' and 'network idle' conditions, indicating execution of arbitrary JavaScript code within a browser context.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

browser_wait Rate-limited

browser_wait 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_wait": {
      "limits": [
        {
          "counter": "browser_wait_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_wait

What does the browser_wait tool do? +

Wait for a condition: URL pattern, CSS selector, text content, custom JS predicate, or network idle. Priority: url > selector > text > fn > networkidle. 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_wait? +

Register the Wmux MCP server in PolicyLayer and add a rule for browser_wait: 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_wait? +

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

Can I rate-limit browser_wait? +

Yes. Add a rate_limit block to the browser_wait 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_wait completely? +

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

browser_wait 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.

// THE FULL RECORD

browser_wait is one line of Wmux's registry record.

The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.

Teams ship this data inside their own products. See what a licence covers →