browser_tab_close · MCP Macaco Playwright MCP: Risk & Policy

WHAT IT DOES

What browser_tab_close does on MCP Macaco Playwright

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

WHY IT NEEDS A POLICY

Why browser_tab_close needs a policy

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

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

browser_tab_close Rate-limited

browser_tab_close 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_tab_close": {
      "limits": [
        {
          "counter": "browser_tab_close_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 MCP Macaco Playwright, so you can run agents against it safely.

FAQ

Questions about browser_tab_close

What does the browser_tab_close tool do? +

Close a browser tab by its index position, or close the currently active tab if no index is specified. After closing, automatically captures a page snapshot of the remaining active tab. It is categorised as a Write tool in the MCP Macaco Playwright 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_tab_close? +

Register the MCP Macaco Playwright MCP server in PolicyLayer and add a rule for browser_tab_close: 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 MCP Macaco Playwright. Nothing to install.

What risk level is browser_tab_close? +

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

Can I rate-limit browser_tab_close? +

Yes. Add a rate_limit block to the browser_tab_close 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_tab_close completely? +

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

browser_tab_close is provided by the MCP Macaco Playwright MCP server (macacoai/mcp-playwright). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.