ui_submit · UI Bridge MCP: Risk & Policy

WHAT IT DOES

What ui_submit does on UI Bridge MCP

AI agents invoke ui_submit 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_submit needs a policy

Submitting a form triggers an external operation with real-world effects (e.g., posting data, creating records, triggering workflows). The action is not merely writing data locally — it dispatches a submission event whose consequences depend on the target form's purpose, potentially causing irreversible or wide-ranging effects.

From the tool's definition "Submit the form containing the element in the runner"

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

ui_submit Rate-limited

ui_submit 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_submit": {
      "limits": [
        {
          "counter": "ui_submit_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_submit

What does the ui_submit tool do? +

Submit the form containing the 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_submit? +

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

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

Can I rate-limit ui_submit? +

Yes. Add a rate_limit block to the ui_submit 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_submit completely? +

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

ui_submit 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.