> ## Documentation Index
> Fetch the complete documentation index at: https://docs.markifact.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Update Transformation

> Replaces a transformation in a Google Tag Manager workspace with a full resource payload

Replaces a transformation in a Google Tag Manager workspace with a full resource payload. Transformations modify event data in a server-side Google Tag Manager container before it reaches tags. Version and publish to take changes live.

| | |
| - | - |
| **App** | Google Tag Manager |
| **Operation ID** | `gtm_update_transformation` |
| **Type** | Action |
| **Connection** | `gtm` (required) |
| **Credits per run** | 1 |
| **Agent / MCP tool** | Yes |
| **Requires approval** | Yes (write operation) |

## Inputs

| Field | Type | Required | Default | Description |
| - | - | - | - | - |
| `account` | DynamicAccount | Yes | - | Select the Google Tag Manager account. |
| `container` | DynamicAccount | Yes | - | Select the container. |
| `workspace` | DynamicAccount | Yes | - | Select the workspace. |
| `transformation` | DynamicAccount | Yes | - | Select the transformation to update, or provide its ID. |
| `transformation_payload` | object or string | Yes | - | Full replacement Transformation resource (object or JSON string) matching the Google Tag Manager API v2 Transformation spec (server containers only); the update replaces the transformation entirely, so include every field it should keep. Workflow: gtm\_get\_transformation -> edit the payload -> gtm\_update\_transformation. Must include name and type; keep the type and the parameter structure of the fetched transformation. The types are tf\_exclude\_params, tf\_allow\_params and tf\_augment\_event; any other type is answered with a bare internal error. Parameter names to exclude or allow are map rows of excludedParamsTable (column excludedParams) or allowedParamsTable (column allowedParams), see gtm\_create\_transformation for a full example. Read-only fields are stripped automatically. |

## Output

**Type**: `Dict`

Returns the updated transformation as provided by the Tag Manager API.


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