Delete all caught emails.
AI agents call mail_dev_clear to permanently remove resources in Yaver — 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 mail_dev_clear doesn't hesitate, doesn't double-check, and doesn't stop at one. Whatever it removes from Yaver is gone — there is no undo for destructive operations.
Attacks that exploit this kind of access
Delete all caught emails. It is categorised as a Destructive tool in the Yaver MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Yaver MCP server in PolicyLayer and add a rule for mail_dev_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 Yaver. Nothing to install.
mail_dev_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 mail_dev_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 mail_dev_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.
mail_dev_clear is provided by the Yaver MCP server (yaver-cli). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.