browser_launch · Js Reverse MCP: Risk & Policy

WHAT IT DOES

What browser_launch does on Js Reverse

AI agents invoke browser_launch to trigger actions in Js Reverse. 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_launch needs a policy

Launching a browser instance is an Execute action because it starts an external application and establishes a connection to the internet/local services. While not inherently destructive, it can be misused to access sensitive sites, perform automated attacks, or interact with malicious content. The headless and proxy capabilities increase the risk of covert abuse.

From the tool's definition Tool description states it 'launches Chrome browser instances' with support for headless mode and proxy configuration.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

browser_launch Rate-limited

browser_launch 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_launch": {
      "limits": [
        {
          "counter": "browser_launch_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 Js Reverse, so you can run agents against it safely.

FAQ

Questions about browser_launch

What does the browser_launch tool do? +

启动Chrome浏览器实例，支持headless模式和代理设置. It is categorised as a Execute tool in the Js Reverse 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_launch? +

Register the Js Reverse MCP server in PolicyLayer and add a rule for browser_launch: 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 Js Reverse. Nothing to install.

What risk level is browser_launch? +

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

Can I rate-limit browser_launch? +

Yes. Add a rate_limit block to the browser_launch 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_launch completely? +

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

browser_launch is provided by the Js Reverse MCP server (jenn619/js-reverse-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.