// MCP TOOL REFERENCE

close_tab_by_id

ServerMCP Browser Tabs Server
CategoryDestructive

WHAT IT DOES

What close_tab_by_id does on MCP Browser Tabs Server

AI agents call close_tab_by_id to permanently remove resources in MCP Browser Tabs Server — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.

THE RISK

Critical Risk

Why close_tab_by_id needs a policy

Closing a browser tab is a destructive action: the tab's session, unsaved content, and navigation history are irrecoverably lost. Unlike write operations, this cannot be undone. The high severity reflects that an AI agent could close important tabs (e.g., active work sessions, unsaved documents) without recovery.

From the tool's definition 'Close a specific tab in Google Chrome using its unique tab ID' — closing a tab is irreversible (any unsaved state or unsubmitted form data in that tab is permanently lost).

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

POLICY

How to control close_tab_by_id

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

policy.json

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

close_tab_by_id 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 Browser Tabs Server — 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 Browser Tabs Server tools

Destructive close_tab ⚠️ LEGACY DANGER: Close a specific tab using window/tab index. HIGH RISK of closing wrong Execute activate_tab_by_id 🔥 PREFERRED METHOD: Activate (focus) a specific tab in Google Chrome using its unique tab Read get_tabs Get all open tabs from Google Chrome browser with unique tab IDs. Each tab has a stable, u

All 4 MCP Browser Tabs Server 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 Browser Tabs Server → 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 close_tab_by_id

What does the close_tab_by_id tool do? +

🔥 PREFERRED METHOD: Close a specific tab in Google Chrome using its unique tab ID. IMMUNE to tab reordering, window changes, and index shifting. Extract the Tab ID from [Tab ID: 1234567890] in get_tabs output. Example: if tab shows. It is categorised as a Destructive tool in the MCP Browser Tabs Server 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 close_tab_by_id? +

Register the MCP Browser Tabs Server MCP server in PolicyLayer and add a rule for close_tab_by_id: 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 Browser Tabs Server. Nothing to install.

What risk level is close_tab_by_id? +

close_tab_by_id 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 close_tab_by_id? +

Yes. Add a rate_limit block to the close_tab_by_id 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 close_tab_by_id completely? +

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

close_tab_by_id is provided by the MCP Browser Tabs Server MCP server (kazuph/mcp-browser-tabs). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every MCP Browser Tabs Server tool call.

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

CHECK YOUR STACK →

Free to start. No card required.

4 MCP Browser Tabs Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.