browser_close_tab

THE RISK

Critical Risk

Why browser_close_tab needs a policy

Closing a browser tab is an irreversible action that destroys the current tab's state, session, and any unsaved data within it. While not as severe as deleting files or dropping databases, it cannot be undone and may cause loss of in-progress work or session state. Given the sibling tools indicate an automated browser context, misuse could disrupt ongoing automated workflows.

From the tool's definition 'Close the current tab' — closing a tab irreversibly terminates the browsing session/state for that tab

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

POLICY

How to control browser_close_tab

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

policy.json

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

browser_close_tab 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 Search — 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 Search tools

Execute browser_evaluate Execute JavaScript in the browser console Execute browser_navigate Navigate to a URL Execute browser_new_tab Open a new tab Execute run_command Run a command on this Execute run_script Run a script on this Execute browser_go_back Go back to the previous page Execute browser_go_forward Go forward to the next page Execute browser_hover Hover an element on the page, Either

All 36 Search 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

Govern code and CI agents → Branch allowlists, approval on merges, and rate caps on the build and pipeline tools agents trigger.
Critical-risk tools in Search → 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 →
PolicyLayer vs alternatives → How deterministic, per-call MCP policy compares with gateways, identity layers, and authorisation platforms.

FAQ

Questions about browser_close_tab

What does the browser_close_tab tool do? +

Close the current tab. It is categorised as a Destructive tool in the Search 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_tab? +

Register the Search MCP server in PolicyLayer and add a rule for browser_close_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 Search. Nothing to install.

What risk level is browser_close_tab? +

browser_close_tab 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_tab? +

Yes. Add a rate_limit block to the browser_close_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_close_tab completely? +

Set action: deny in the PolicyLayer policy for browser_close_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_close_tab? +

browser_close_tab is provided by the Search MCP server (@agent-infra/mcp-server-search). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Search tool call.

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

CHECK YOUR STACK →