cancel_scheduled
Cancel a pending scheduled message. Requires TREKMAIL_ALLOW_DESTRUCTIVE=true.
This record as markdown: /tools/trekmail-mcp-server/cancel-scheduled.md
What cancel_scheduled does on TrekMail MCP Server
AI agents call cancel_scheduled to permanently remove resources in TrekMail MCP Server, typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
Why cancel_scheduled is rated Critical
Cancelling scheduled messages is a destructive operation that permanently prevents a queued message from being sent. Once cancelled, the scheduled message cannot be recovered. The explicit requirement for a destructive flag in the environment variable confirms the developers classified this as a destructive action.
From the tool's definition Tool explicitly requires TREKMAIL_ALLOW_DESTRUCTIVE=true environment variable, and performs 'cancel' operation on scheduled messages—an irreversible action that destroys pending message sends and cannot be undone.
Attacks that exploit this kind of access
The rule that runs cancel_scheduled safely
PolicyLayer is an MCP gateway: it sits between your AI agents and TrekMail MCP Server, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For cancel_scheduled, this is the rule to start with:
cancel_scheduled is removed from the agent's tool list entirely, so the agent never calls it. The rest of the server keeps working.
The button opens the PolicyLayer dashboard: create your workspace, connect TrekMail MCP Server, apply this rule, and every cancel_scheduled call is checked against it from then on.
Questions about cancel_scheduled
Cancel a pending scheduled message. Requires TREKMAIL_ALLOW_DESTRUCTIVE=true. It is categorised as a Destructive tool in the TrekMail MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the TrekMail MCP Server MCP server in PolicyLayer and add a rule for cancel_scheduled: 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 TrekMail MCP Server. Nothing to install.
cancel_scheduled 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 cancel_scheduled 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 cancel_scheduled. 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.
cancel_scheduled is provided by the TrekMail MCP Server MCP server (trekmail/mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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