browser_close_all · Ma Browser MCP: Risk & Policy

WHAT IT DOES

What browser_close_all does on Ma Browser

AI agents use browser_close_all to create or update resources in Ma Browser — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Ma Browser environment.

WHY IT NEEDS A POLICY

Why browser_close_all needs a policy

An AI agent can call browser_close_all faster than any human can review — one bad instruction and it creates or modifies resources in Ma Browser by the hundred, each call as confident as the last.

Risk signalsBulk/mass operation — affects multiple targets

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

browser_close_all Rate-limited

browser_close_all stays usable, but capped — an agent stuck in a loop can't make hundreds of changes 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_close_all": {
      "limits": [
        {
          "counter": "browser_close_all_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Ma Browser, so you can run agents against it safely.

FAQ

Questions about browser_close_all

What does the browser_close_all tool do? +

Close tabs opened by ma-browser during the current MCP session. It is categorised as a Write tool in the Ma Browser MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on browser_close_all? +

Register the Ma Browser MCP server in PolicyLayer and add a rule for browser_close_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 Ma Browser. Nothing to install.

What risk level is browser_close_all? +

browser_close_all is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit browser_close_all? +

Yes. Add a rate_limit block to the browser_close_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 browser_close_all completely? +

Set action: deny in the PolicyLayer policy for browser_close_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 browser_close_all? +

browser_close_all is provided by the Ma Browser MCP server (zzhan111/multi-agents-browser). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.