ui_select · UI Bridge MCP: Risk & Policy

WHAT IT DOES

What ui_select does on UI Bridge MCP

AI agents invoke ui_select 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_select needs a policy

This tool performs a UI interaction by selecting an option in a dropdown/select element. It goes beyond reading data and beyond just writing data — it executes a UI action that triggers external application behavior. The effect depends on which option is selected and what the dropdown controls, which could cause downstream state changes in the application.

From the tool's definition 'Select an option in a dropdown/select element in the runner' — triggers a UI interaction (selection action) on an external application's UI element

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

ui_select Rate-limited

ui_select 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_select": {
      "limits": [
        {
          "counter": "ui_select_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_select

What does the ui_select tool do? +

Select an option in a dropdown/select 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_select? +

Register the UI Bridge MCP server in PolicyLayer and add a rule for ui_select: 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_select? +

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

Can I rate-limit ui_select? +

Yes. Add a rate_limit block to the ui_select 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_select completely? +

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

ui_select 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.