browser_close

THE RISK

Critical Risk

Why browser_close needs a policy

Closing the browser is an irreversible action that destroys the current browser session and all associated in-memory state (open tabs, loaded pages, unsaved form data, etc.). While cookies are preserved in the persistent profile, the active session itself cannot be restored. This qualifies as Destructive given the unrecoverable loss of session state.

From the tool's definition 'Close the browser' — terminates the browser session irreversibly; any unsaved state, open tabs, or in-progress operations are lost and cannot be recovered.

Documented attack patterns abuse exactly the kind of access browser_close gives an agent:

POLICY

How to control browser_close

PolicyLayer is an MCP gateway — it sits between your AI agents and MCP Camoufox, and nothing reaches the server without passing your rules. This is the rule we recommend for browser_close:

policy.json

{
  "version": "1",
  "default": "deny",
  "hide": [
    "browser_close"
  ]
}

browser_close disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.

Create a free account and register MCP Camoufox — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RESTRICT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More MCP Camoufox tools

Destructive cookie_delete Delete cookies. Both empty = clear all. Destructive localstorage_clear Clear all localStorage. Destructive reset_profile Delete the persistent profile (~/.camoufox-mcp/profile) entirely. Destructive tab_close Close a tab by index (-1 = active), or by url_contains. Execute batch_actions Execute multiple actions in one call. Each action: {type, ref?, value?, text?, key?, url?} Execute browser_launch Launch Camoufox stealth browser and navigate to URL. Browser persists between calls. Execute evaluate Execute JavaScript in page context. Execute frame_evaluate Execute JavaScript inside a specific frame/iframe.

All 102 MCP Camoufox tools →

Destructive tools on other servers

Android Forensics ADB MCP Server create_full_backup 0xarchive web3_revoke_key Frida Game Hacking MCP clear_scan cPanel MCP Server clear_spam_box

Go deeper

Critical-risk tools in MCP Camoufox → Every critical-risk tool this server exposes, in one view.
All critical-risk MCP tools → Every critical-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Blast radius → How much damage one compromised or confused agent can do — and how to bound it.
Tool call approval → Approval gates on individual tool calls: auto-allow, prompt, or deny.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about browser_close

What does the browser_close tool do? +

Close the browser. Cookies are preserved in the persistent profile (~/.camoufox-mcp/profile). It is categorised as a Destructive tool in the MCP Camoufox MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.

How do I enforce a policy on browser_close? +

Register the MCP Camoufox 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 MCP Camoufox. Nothing to install.

What risk level is browser_close? +

browser_close is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

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 MCP Camoufox MCP server (robithyusuf/mcp-camoufox). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every MCP Camoufox tool call.

Start from MCP Camoufox, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →