Revert a previous write operation by its history entry ID. Note: Account creation cannot be undone (YNAB API limitation).
AI agents call undo_operation to permanently remove resources in YNAB MCP Server — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
Undoing a write operation irreversibly removes or negates previously committed changes. While framed as a 'revert', the effect is to eliminate the prior state/action, which cannot itself be un-undone through this system (no redo mechanism described). This is analogous to a delete of the prior operation's effects, making it Destructive.
From the tool's definition Revert a previous write operation by its history entry ID
Attacks that exploit this kind of access
Revert a previous write operation by its history entry ID. Note: Account creation cannot be undone (YNAB API limitation). It is categorised as a Destructive tool in the YNAB MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the YNAB MCP Server MCP server in PolicyLayer and add a rule for undo_operation: 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 YNAB MCP Server. Nothing to install.
undo_operation 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 undo_operation 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 undo_operation. 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.
undo_operation is provided by the YNAB MCP Server MCP server (jeangnc/ynab-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
undo_operation is one line of YNAB MCP Server's registry record.
The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.
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