browser_tabs · MCP Playwright Server MCP: Risk & Policy

WHAT IT DOES

What browser_tabs does on MCP Playwright Server

AI agents invoke browser_tabs to trigger actions in MCP Playwright Server. 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_tabs needs a policy

This tool spans multiple operations: listing tabs is Read, but creating, closing, and selecting tabs are browser control actions that trigger external operations (browser state changes). Creating and closing tabs are side-effectful operations controlling the browser environment. Per severity rules, Execute is the most severe applicable category.

From the tool's definition List, create, close, or select browser tabs

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

browser_tabs Rate-limited

browser_tabs 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_tabs": {
      "limits": [
        {
          "counter": "browser_tabs_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 MCP Playwright Server, so you can run agents against it safely.

FAQ

Questions about browser_tabs

What does the browser_tabs tool do? +

List, create, close, or select browser tabs. It is categorised as a Execute tool in the MCP Playwright Server 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_tabs? +

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

What risk level is browser_tabs? +

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

Can I rate-limit browser_tabs? +

Yes. Add a rate_limit block to the browser_tabs 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_tabs completely? +

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

browser_tabs is provided by the MCP Playwright Server MCP server (j0hanz/playwright-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.