# browser_eval

Execute JavaScript in the browser and return the result.

Agent View of the PolicyLayer registry record for `browser_eval`. HTML page: https://policylayer.com/tools/salviz-termux-browser-pilot/browser-eval

## Facts

- Tool: `browser_eval`
- Server: Termux Browser Pilot (`salviz/termux-browser-pilot`) — https://policylayer.com/tools/salviz-termux-browser-pilot.md
- Homepage: https://github.com/salviz/termux-browser-pilot
- 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": "browser_eval",
    "arguments": {}
  }
}
```

## Why browser_eval is rated High

This tool executes arbitrary JavaScript code in a live browser context, which can perform any action the browser permits: data exfiltration, credential theft, navigation to malicious sites, form submission, DOM manipulation, and interaction with web services. The blast radius is substantial if an AI agent crafts malicious JavaScript payloads.

From the tool's own definition: "Tool name 'browser_eval' and description 'Execute JavaScript in the browser and return the result' explicitly indicate arbitrary code execution capability."

## Use case

AI agents invoke browser_eval to trigger actions in Termux Browser Pilot. 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 Termux Browser Pilot:

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

## Other tools on Termux Browser Pilot (147)

- `browser_auth_delete` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-auth-delete.md
- `browser_console_clear` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-console-clear.md
- `browser_cookies_clear` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-cookies-clear.md
- `browser_dialog_clear` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-dialog-clear.md
- `browser_events_clear` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-events-clear.md
- `browser_headers_clear` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-headers-clear.md
- `browser_mock_clear` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-mock-clear.md
- `browser_mutations_clear` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-mutations-clear.md
- `browser_network_clear` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-network-clear.md
- `browser_profile_delete` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-profile-delete.md
- `browser_responses_clear` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-responses-clear.md
- `browser_session_delete` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-session-delete.md
- `browser_snapshot_delete` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-snapshot-delete.md
- `browser_storage_clear` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-storage-clear.md
- `browser_storage_remove` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-storage-remove.md
- `browser_tab_close` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-tab-close.md
- `browser_unblock` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-unblock.md
- `browser_window_close` — Destructive — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-window-close.md
- `browser_attr_remove` — Execute — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-attr-remove.md
- `browser_attr_set` — Execute — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-attr-set.md
- `browser_auth_load` — Execute — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-auth-load.md
- `browser_back` — Execute — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-back.md
- `browser_block` — Execute — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-block.md
- `browser_check` — Execute — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-check.md
- `browser_click` — Execute — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-click.md
- `browser_console_start` — Execute — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-console-start.md
- `browser_console_stop` — Execute — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-console-stop.md
- `browser_cookies_load` — Execute — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-cookies-load.md
- `browser_css_inject` — Execute — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-css-inject.md
- `browser_css_remove` — Execute — https://policylayer.com/tools/salviz-termux-browser-pilot/browser-css-remove.md
- …and 117 more: https://policylayer.com/tools/salviz-termux-browser-pilot.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`

---

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