sdk_wait_for_change · UI Bridge MCP: Risk & Policy

WHAT IT DOES

What sdk_wait_for_change does on UI Bridge MCP

AI agents invoke sdk_wait_for_change 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 sdk_wait_for_change needs a policy

This tool executes a monitoring/polling operation on an external UI system (SDK mode). While it doesn't directly modify data or delete anything, it actively interacts with and monitors external application state, making it an Execute-class tool.

From the tool's definition Tool performs 'wait for the UI to change matching a predicate' with polling behavior, which actively monitors and potentially triggers or responds to UI state changes. This is an active operation that can affect external UI behavior.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

sdk_wait_for_change Rate-limited

sdk_wait_for_change 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": {
    "sdk_wait_for_change": {
      "limits": [
        {
          "counter": "sdk_wait_for_change_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 sdk_wait_for_change

What does the sdk_wait_for_change tool do? +

Wait for the UI to change matching a predicate. Polls until a matching change is detected or timeout. 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 sdk_wait_for_change? +

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

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

Can I rate-limit sdk_wait_for_change? +

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

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

sdk_wait_for_change 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.