# query_selector

Query DOM elements using CSS selector

Agent View of the PolicyLayer registry record for `query_selector`. HTML page: https://policylayer.com/tools/browser/query-selector

## Facts

- Tool: `query_selector`
- 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: Read (Low risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Allowed

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

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

## Why query_selector is rated Low

This tool retrieves DOM element information based on CSS selectors. It reads the browser's current DOM state without modifying, executing code, or triggering external operations. While it operates in a browser context (where other sibling tools like execute_script are Execute category), query_selector itself is a passive read operation analogous to get_* tools on this server.

From the tool's own definition: "Tool description states 'Query DOM elements using CSS selector' - a pure query operation with no modification, execution, or side effects."

## Use case

AI agents call query_selector to retrieve information from Browser without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

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

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "query_selector": {}
  }
}
```

## 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_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
- `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