# Update a library block

> The update_library_entry MCP tool: update a library block.

`update_library_entry` · writes · idempotent

[REST: `PATCH /v1/library/entries/{entryId}`](https://api.bymundi.com/docs/reference/library.entries.update.md)

## What the model reads

Renames or re-tags a library entry, and/or replaces its content with a block of a trip (`fromTrip: { tripId, blockId }`, same block type). To change what is inside a saved block: insert it into a trip (insert_library_entry), edit it there, then call this with `fromTrip`. undo_change reverts it.

Permissions: catalog:write.
Undo: the result names a change id; undo_change reverts it.

## Input

| Field | Type | Required | Description |
|---|---|---|---|
| `entryId` | uuid | yes |  |
| `title` | string |  | max 200 chars |
| `tags` | string[] |  | Replaces the tags; lowercased. max 20 items |
| `fromTrip` | object |  |  |
| `fromTrip.tripId` | uuid | yes |  |
| `fromTrip.blockId` | string | yes | The block's id or its short ref from get_itinerary. max 64 chars |
| `expectedUpdatedAt` | datetime |  |  |

## Input schema (JSON)

```json
{
  "type": "object",
  "properties": {
    "entryId": {
      "type": "string",
      "format": "uuid"
    },
    "title": {
      "type": "string",
      "minLength": 1,
      "maxLength": 200
    },
    "tags": {
      "type": "array",
      "items": {
        "type": "string",
        "minLength": 1,
        "maxLength": 60
      },
      "maxItems": 20,
      "description": "Replaces the tags; lowercased."
    },
    "fromTrip": {
      "type": "object",
      "properties": {
        "tripId": {
          "type": "string",
          "format": "uuid"
        },
        "blockId": {
          "type": "string",
          "minLength": 1,
          "maxLength": 64,
          "description": "The block's id or its short ref from get_itinerary."
        }
      },
      "required": [
        "tripId",
        "blockId"
      ],
      "additionalProperties": false
    },
    "expectedUpdatedAt": {
      "type": "string",
      "format": "date-time"
    }
  },
  "required": [
    "entryId"
  ],
  "additionalProperties": false
}
```