# compare_viewports

A read tool on the UI Analyzer MCP Server MCP server.

Agent View of the PolicyLayer registry record for `compare_viewports`. HTML page: https://policylayer.com/tools/0x-professor-uianalyzermcp/compare-viewports

## Facts

- Tool: `compare_viewports`
- Server: UI Analyzer MCP Server (`0x-professor/uianalyzermcp`) — https://policylayer.com/tools/0x-professor-uianalyzermcp.md
- Homepage: https://github.com/0x-Professor/UIAnalyzerMCP
- Risk category: Read (Low risk)
- Registry record: grade A, 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": "compare_viewports",
    "arguments": {}
  }
}
```

## Why compare_viewports is rated Low

This tool fits the Read category: it retrieves or compares UI state information without modifying, deleting, or executing external operations. The empty description lowers confidence slightly, but context from sibling tools and the server's stated purpose (analysis for AI coding assistants) strongly suggests it performs viewport comparison for inspection purposes only.

From the tool's own definition: "Tool name 'compare_viewports' and server description indicate analysis/inspection capability. The server uses Playwright for analyzing website UIs and providing instructions."

## Use case

AI agents call compare_viewports to retrieve information from UI Analyzer MCP Server 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 UI Analyzer MCP Server:

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

## Other tools on UI Analyzer MCP Server (7)

- `analyze_page` — Read — https://policylayer.com/tools/0x-professor-uianalyzermcp/analyze-page.md
- `get_accessibility_snapshot` — Read — https://policylayer.com/tools/0x-professor-uianalyzermcp/get-accessibility-snapshot.md
- `get_dom_overview` — Read — https://policylayer.com/tools/0x-professor-uianalyzermcp/get-dom-overview.md
- `get_element_details` — Read — https://policylayer.com/tools/0x-professor-uianalyzermcp/get-element-details.md
- `get_fix_instructions` — Read — https://policylayer.com/tools/0x-professor-uianalyzermcp/get-fix-instructions.md
- `get_screenshot` — Read — https://policylayer.com/tools/0x-professor-uianalyzermcp/get-screenshot.md
- `get_tech_stack` — Read — https://policylayer.com/tools/0x-professor-uianalyzermcp/get-tech-stack.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=0x-professor-uianalyzermcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/0x-professor-uianalyzermcp