ui_clipboard_write · UI Bridge MCP: Risk & Policy

WHAT IT DOES

What ui_clipboard_write does on UI Bridge MCP

AI agents use ui_clipboard_write to create or update resources in UI Bridge MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your UI Bridge MCP environment.

WHY IT NEEDS A POLICY

Why ui_clipboard_write needs a policy

This tool modifies system state (clipboard content) reversibly. While clipboard writes are not destructive, they can interfere with user workflows, enable data exfiltration chains, or facilitate prompt injection attacks if an agent writes malicious content. However, the action is technically reversible (clipboard can be overwritten) and has no direct financial impact.

From the tool's definition Tool name 'ui_clipboard_write' and description 'Write text to the system clipboard (Control mode)' explicitly performs a write operation to system clipboard.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

ui_clipboard_write Rate-limited

ui_clipboard_write stays usable, but capped — an agent stuck in a loop can't make hundreds of changes 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_clipboard_write": {
      "limits": [
        {
          "counter": "ui_clipboard_write_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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_clipboard_write

What does the ui_clipboard_write tool do? +

Write text to the system clipboard (Control mode). It is categorised as a Write tool in the UI Bridge MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on ui_clipboard_write? +

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

ui_clipboard_write is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit ui_clipboard_write? +

Yes. Add a rate_limit block to the ui_clipboard_write 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_clipboard_write completely? +

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

ui_clipboard_write 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.