ui_check · UI Bridge MCP: Risk & Policy

WHAT IT DOES

What ui_check does on UI Bridge MCP

AI agents invoke ui_check to trigger actions in UI Bridge MCP. 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 ui_check needs a policy

Checking a checkbox is a UI action that modifies the state of a UI element in an external application. This goes beyond reading data and constitutes executing an interaction. The effect depends on which checkbox is targeted, potentially triggering downstream actions or configuration changes, placing it in the Execute category.

From the tool's definition "Check a checkbox element in the runner" — triggers a UI interaction (checking a checkbox) in an external application, which constitutes an external operation whose effects depend on the target element.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

ui_check Rate-limited

ui_check 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": {
    "ui_check": {
      "limits": [
        {
          "counter": "ui_check_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 UI Bridge MCP, so you can run agents against it safely.

FAQ

Questions about ui_check

What does the ui_check tool do? +

Check a checkbox element in the runner. It is categorised as a Execute tool in the UI Bridge MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on ui_check? +

Register the UI Bridge MCP server in PolicyLayer and add a rule for ui_check: 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 UI Bridge MCP. Nothing to install.

What risk level is ui_check? +

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

Can I rate-limit ui_check? +

Yes. Add a rate_limit block to the ui_check 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 ui_check completely? +

Set action: deny in the PolicyLayer policy for ui_check. 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 ui_check? +

ui_check is provided by the UI Bridge MCP server (qontinui/ui-bridge-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.