# Undo a change

> The undo_change MCP tool: undo a change.

`undo_change` · writes

[REST: `POST /v1/changes/{changeId}/revert`](https://api.bymundi.com/docs/reference/changes.revert.md)

## What the model reads

Undoes a change, as Undo does, and needs the permissions of the operation that made it. It is conditional: if anything the change touched was edited since, it refuses with a 409 and changes nothing (the change stays `applied`). If a LATER step is refused, the change becomes `failed` and the error says `partial: true`. Only an `applied` change can be undone, and an undo cannot itself be undone: make the change again.

Permissions: any valid key.
This cannot be undone.

## Input

| Field | Type | Required | Description |
|---|---|---|---|
| `changeId` | uuid | yes |  |

## Input schema (JSON)

```json
{
  "type": "object",
  "properties": {
    "changeId": {
      "type": "string",
      "format": "uuid"
    }
  },
  "required": [
    "changeId"
  ],
  "additionalProperties": false
}
```