capture_url · Componentize MCP: Risk & Policy

WHAT IT DOES

What capture_url does on Componentize

AI agents invoke capture_url to trigger actions in Componentize. 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.

WHY IT NEEDS A POLICY

Why capture_url needs a policy

This tool takes a URL, navigates to it (external network request/browser action), captures a screenshot, and then analyzes it. The act of fetching and rendering an arbitrary URL is an external operation whose effects depend on the argument — triggering a browser-like action against a third-party resource.

From the tool's definition 截图一个网址并分析其中的 UI 组件 (screenshot a URL and analyze UI components within it)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

capture_url Rate-limited

capture_url stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "capture_url": {
      "limits": [
        {
          "counter": "capture_url_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Componentize, so you can run agents against it safely.

FAQ

Questions about capture_url

What does the capture_url tool do? +

截图一个网址并分析其中的 UI 组件. It is categorised as a Execute tool in the Componentize MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on capture_url? +

Register the Componentize MCP server in PolicyLayer and add a rule for capture_url: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Componentize. Nothing to install.

What risk level is capture_url? +

capture_url is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit capture_url? +

Yes. Add a rate_limit block to the capture_url rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block capture_url completely? +

Set action: deny in the PolicyLayer policy for capture_url. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides capture_url? +

capture_url is provided by the Componentize MCP server (monlohua/componentize). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.