browser_switch_tab · Byob MCP: Risk & Policy

WHAT IT DOES

What browser_switch_tab does on Byob

AI agents invoke browser_switch_tab to trigger actions in Byob. 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_switch_tab needs a policy

This tool triggers a browser UI action — switching focus to a specific tab — which is an external operation affecting the browser state. It doesn't read, write, or delete data, but it executes a browser control action. Severity is low since it only changes tab focus with no data modification or destructive effects.

From the tool's definition Bring the given tab to the foreground (focus its window + make it active)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

browser_switch_tab Rate-limited

browser_switch_tab 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_switch_tab": {
      "limits": [
        {
          "counter": "browser_switch_tab_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 Byob, so you can run agents against it safely.

FAQ

Questions about browser_switch_tab

What does the browser_switch_tab tool do? +

Bring the given tab to the foreground (focus its window + make it active). It is categorised as a Execute tool in the Byob 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_switch_tab? +

Register the Byob MCP server in PolicyLayer and add a rule for browser_switch_tab: 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 Byob. Nothing to install.

What risk level is browser_switch_tab? +

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

Can I rate-limit browser_switch_tab? +

Yes. Add a rate_limit block to the browser_switch_tab 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_switch_tab completely? +

Set action: deny in the PolicyLayer policy for browser_switch_tab. 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_switch_tab? +

browser_switch_tab is provided by the Byob MCP server (wxtsky/byob). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.