browser_close

Close the browser

SERVERCoWork OS SOURCECoWork-OS/CoWork-OS

High RISK CLASS

Category Execute

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/cowork-os/browser-close.md

WHAT IT DOES

What browser_close does on CoWork OS

AI agents invoke browser_close to trigger actions in CoWork OS. 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.

RISK

Why browser_close is rated High

Closing a browser is an external operation that terminates a running process/session. It is an action with real side effects (ending a browser session, potentially losing unsaved state), making it Execute. It is not purely destructive (no data is permanently deleted), but it does trigger an external operation. Severity is medium because misuse could interrupt active browser sessions or cause loss of unsaved work.

From the tool's definition Close the browser

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs browser_close safely

PolicyLayer is an MCP gateway: it sits between your AI agents and CoWork OS, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For browser_close, this is the rule to start with:

browser_close Rate-limited

browser_close 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_close": {
      "limits": [
        {
          "counter": "browser_close_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect CoWork OS, apply this rule, and every browser_close call is checked against it from then on.

FAQ

Questions about browser_close

What does the browser_close tool do? +

Close the browser. It is categorised as a Execute tool in the CoWork OS 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_close? +

Register the CoWork OS MCP server in PolicyLayer and add a rule for browser_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 CoWork OS. Nothing to install.

What risk level is browser_close? +

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

Can I rate-limit browser_close? +

Yes. Add a rate_limit block to the browser_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_close completely? +

Set action: deny in the PolicyLayer policy for browser_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_close? +

browser_close is provided by the CoWork OS MCP server (CoWork-OS/CoWork-OS). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

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