# browser_evaluate

Execute JavaScript code in the browser context

Agent View of the PolicyLayer registry record for `browser_evaluate`. HTML page: https://policylayer.com/tools/cowork-os/browser-evaluate

## Facts

- Tool: `browser_evaluate`
- Server: CoWork OS (`CoWork-OS/CoWork-OS`) — https://policylayer.com/tools/cowork-os.md
- Homepage: https://github.com/CoWork-OS/CoWork-OS
- 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_evaluate",
    "arguments": {}
  }
}
```

## Why browser_evaluate is rated High

This is a classic Execute tool: it runs code (JavaScript) whose effects depend entirely on the argument (the code string). The browser context gives it access to sensitive user data, authentication tokens, and the ability to perform actions on any visited website.

From the tool's own definition: "'Execute JavaScript code in the browser context' — the tool runs arbitrary JavaScript in a live browser environment, which can access DOM, modify page state, trigger navigation, exfiltrate data, or perform actions on behalf of the user."

## Use case

AI agents invoke browser_evaluate to trigger actions in CoWork OS. 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 CoWork OS:

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

## Other tools on CoWork OS (341)

- `cancel_agent` — Destructive — https://policylayer.com/tools/cowork-os/cancel-agent.md
- `cancel_video_generation_job` — Destructive — https://policylayer.com/tools/cowork-os/cancel-video-generation-job.md
- `cloud_sandbox_delete` — Destructive — https://policylayer.com/tools/cowork-os/cloud-sandbox-delete.md
- `delete_file` — Destructive — https://policylayer.com/tools/cowork-os/delete-file.md
- `disable_macos_launch_agents` — Destructive — https://policylayer.com/tools/cowork-os/disable-macos-launch-agents.md
- `domain_dns_delete` — Destructive — https://policylayer.com/tools/cowork-os/domain-dns-delete.md
- `google-workspace.calendar_event_delete` — Destructive — https://policylayer.com/tools/cowork-os/google-workspace.calendar-event-delete.md
- `google-workspace.slides_delete_slide` — Destructive — https://policylayer.com/tools/cowork-os/google-workspace.slides-delete-slide.md
- `google-workspace.tasks_clear_completed` — Destructive — https://policylayer.com/tools/cowork-os/google-workspace.tasks-clear-completed.md
- `google-workspace.tasks_delete` — Destructive — https://policylayer.com/tools/cowork-os/google-workspace.tasks-delete.md
- `google-workspace.tasks_lists_delete` — Destructive — https://policylayer.com/tools/cowork-os/google-workspace.tasks-lists-delete.md
- `kg_delete_edge` — Destructive — https://policylayer.com/tools/cowork-os/kg-delete-edge.md
- `kg_delete_entity` — Destructive — https://policylayer.com/tools/cowork-os/kg-delete-entity.md
- `skill_delete` — Destructive — https://policylayer.com/tools/cowork-os/skill-delete.md
- `supermemory_forget` — Destructive — https://policylayer.com/tools/cowork-os/supermemory-forget.md
- `blender.render_view` — Execute — https://policylayer.com/tools/cowork-os/blender.render-view.md
- `browser_act_batch` — Execute — https://policylayer.com/tools/cowork-os/browser-act-batch.md
- `browser_attach` — Execute — https://policylayer.com/tools/cowork-os/browser-attach.md
- `browser_back` — Execute — https://policylayer.com/tools/cowork-os/browser-back.md
- `browser_click` — Execute — https://policylayer.com/tools/cowork-os/browser-click.md
- `browser_close` — Execute — https://policylayer.com/tools/cowork-os/browser-close.md
- `browser_close_tab` — Execute — https://policylayer.com/tools/cowork-os/browser-close-tab.md
- `browser_drag` — Execute — https://policylayer.com/tools/cowork-os/browser-drag.md
- `browser_emulate` — Execute — https://policylayer.com/tools/cowork-os/browser-emulate.md
- `browser_fill` — Execute — https://policylayer.com/tools/cowork-os/browser-fill.md
- `browser_forward` — Execute — https://policylayer.com/tools/cowork-os/browser-forward.md
- `browser_handle_dialog` — Execute — https://policylayer.com/tools/cowork-os/browser-handle-dialog.md
- `browser_hover` — Execute — https://policylayer.com/tools/cowork-os/browser-hover.md
- `browser_navigate` — Execute — https://policylayer.com/tools/cowork-os/browser-navigate.md
- `browser_press` — Execute — https://policylayer.com/tools/cowork-os/browser-press.md
- …and 311 more: https://policylayer.com/tools/cowork-os.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=cowork-os · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/cowork-os