# Reducing Payload Size
By default, utility hooks will **not** send their full schema unless the `Send full schema in utility hooks` setting in the page editor is enabled. This allows the browser to send a reduced data payload resulting in faster transfer times.
In the page editor, that setting is available on the `Integration` tab:
## What Gets Sent By Default
When `sendFullSchema` is **off**, BetterForms trims the utility-hook payload before sending it to FileMaker.
In that reduced mode, BetterForms removes the large page/schema structures and keeps a lightweight `form` object with the current `hookSetName`.
Use full-schema payloads only when your FileMaker hook really needs page/schema/site context.
## Controlling `payload.model`
For `runUtilityHook`, BetterForms supports two browser-side ways to reduce or reshape the `model` that is sent:
### `options.modelFilterKeys`
`modelFilterKeys` keeps only selected keys from the current page model before the payload is sent.
This follows Lodash `pick` behavior on the current model object.
```json
{
"action": "runUtilityHook",
"options": {
"modelFilterKeys": ["activeContact"],
"type": "save"
}
}
```
Use this when you want to send a smaller subset of the existing page model.
### `options.model`
`model` overrides the outgoing model payload entirely.
This is commonly paired with a `function` or `model_calc` pattern that builds a smaller object just for the hook call.
```json
{
"action": "runUtilityHook",
"options": {
"model": {
"activeContact": {
"id": "123"
}
},
"type": "save"
}
}
```
Use this when you want to send a custom object instead of the page's normal model shape.
## Merge Behavior On Return
When `runUtilityHook` uses `options.model` or `options.modelFilterKeys`, BetterForms marks the request with:
* `state.modelUpdateMode = "merge"`
On the way back from FileMaker:
* if the hook returns `result.model` and no explicit `state.modelUpdateMode`, BetterForms now defaults to `merge`
* merge mode applies the returned keys onto the current client model
* replace mode must be requested explicitly with `state.modelUpdateMode = "replace"`
This matters because merge mode preserves client-only reactive keys while still applying the server's returned values.
## Practical Example
```json
{
"action": "runUtilityHook",
"options": {
"modelFilterKeys": ["activeContact"],
"type": "save"
}
}
```
If FileMaker returns:
```json
{
"model": {
"activeContact": {
"id": "123",
"status": "saved"
}
}
}
```
BetterForms merges that returned object into the existing page model unless the response explicitly sets `state.modelUpdateMode` to `replace`.
---
# Agent Instructions: Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter:
```
GET https://docs.klai.studio/reference/hooksoverview/env_vars.md?ask=
```
The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.