# close_tab

Close tab (tab id)

Agent View of the PolicyLayer registry record for `close_tab`. HTML page: https://policylayer.com/tools/browser/close-tab

## Facts

- Tool: `close_tab`
- Server: Browser (`mcp-server-browser`) — https://policylayer.com/tools/browser.md
- Install: `npx -y mcp-server-browser`
- Homepage: git+https://github.com/mvtcode/mcp-server-browser.git
- Risk category: Destructive (Critical risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Hidden

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "close_tab",
    "arguments": {}
  }
}
```

## Why close_tab is rated Critical

Closing a tab cannot be undone; any unsaved form data, page state, or session information is permanently lost. While not as severe as deleting files or dropping databases, it is an irreversible action that could disrupt ongoing user sessions or lose work. Severity is medium because blast radius is limited to a single browser tab.

From the tool's own definition: "'Close tab' - closing a browser tab is an irreversible action that destroys the tab's state, session, and any unsaved content"

## Use case

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

## Recommended policy (PolicyLayer)

Verdict: **Hidden**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Browser:

```json
{
  "version": "1",
  "default": "deny",
  "hide": [
    "close_tab"
  ]
}
```

## Other tools on Browser (18)

- `execute_script` — Execute — https://policylayer.com/tools/browser/execute-script.md
- `new_tab` — Execute — https://policylayer.com/tools/browser/new-tab.md
- `pin_active_tab` — Execute — https://policylayer.com/tools/browser/pin-active-tab.md
- `set_active_tab` — Execute — https://policylayer.com/tools/browser/set-active-tab.md
- `set_url_tab` — Execute — https://policylayer.com/tools/browser/set-url-tab.md
- `get_active_tab` — Read — https://policylayer.com/tools/browser/get-active-tab.md
- `get_console_debug` — Read — https://policylayer.com/tools/browser/get-console-debug.md
- `get_console_error` — Read — https://policylayer.com/tools/browser/get-console-error.md
- `get_console_info` — Read — https://policylayer.com/tools/browser/get-console-info.md
- `get_console_log` — Read — https://policylayer.com/tools/browser/get-console-log.md
- `get_console_warn` — Read — https://policylayer.com/tools/browser/get-console-warn.md
- `get_list_tab` — Read — https://policylayer.com/tools/browser/get-list-tab.md
- `get_network_request` — Read — https://policylayer.com/tools/browser/get-network-request.md
- `get_network_request_detail` — Read — https://policylayer.com/tools/browser/get-network-request-detail.md
- `get_tab_content_html` — Read — https://policylayer.com/tools/browser/get-tab-content-html.md
- `get_tab_content_text` — Read — https://policylayer.com/tools/browser/get-tab-content-text.md
- `query_selector` — Read — https://policylayer.com/tools/browser/query-selector.md
- `unpin_active_tab` — Write — https://policylayer.com/tools/browser/unpin-active-tab.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

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Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=browser · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/browser