# set_active_tab

Set active tab (tab id)

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

## Facts

- Tool: `set_active_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: Execute (High risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Rate-limited

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

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

## Why set_active_tab is rated High

Switching the active tab is a browser control action with side effects (changes UI state and focus), placing it in the Execute category. While not destructive or data-modifying, it triggers an external operation in the browser. Misuse could redirect agent attention or disrupt user workflow, but blast radius is relatively limited.

From the tool's own definition: "Set active tab (tab id) — triggers a browser action that changes the active/focused tab"

## Use case

AI agents invoke set_active_tab to trigger actions in Browser. 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.

## Recommended policy (PolicyLayer)

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

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "set_active_tab": {
      "limits": [
        {
          "counter": "set_active_tab_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Browser (18)

- `close_tab` — Destructive — https://policylayer.com/tools/browser/close-tab.md
- `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_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