Clear the value of an input element in the runner
AI agents call ui_clear to permanently remove resources in UI Bridge MCP — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
An AI agent that decides to call ui_clear doesn't hesitate, doesn't double-check, and doesn't stop at one. Whatever it removes from UI Bridge MCP is gone — there is no undo for destructive operations.
Attacks that exploit this kind of access
Clear the value of an input element in the runner. It is categorised as a Destructive tool in the UI Bridge MCP MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the UI Bridge MCP server in PolicyLayer and add a rule for ui_clear: 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.
ui_clear is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the ui_clear 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.
Set action: deny in the PolicyLayer policy for ui_clear. 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.
ui_clear 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.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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