---
title: "act: watch"
description: "a public entity to a watched identity, with its monitor armed"
section: reference
address: /reference/act/watch
contract: 0476e35e6e275db5
---

# act: watch

a public entity to a watched identity, with its monitor armed

[figure: The caller sends WatchInput to /v1/act/watch. The platform returns a card whose body is WatchedIdentity.]

<span class="op-method">POST</span><span class="op-path">/v1/act/watch</span>

Watch an identity. The call needs the brand rung under a token with the act grant, and it is served by the platform.

The route takes [WatchInput](/concepts/watchinput) and returns a card whose body is [WatchedIdentity](/concepts/watchedidentity).



## Request body
The request body is [WatchInput](/concepts/watchinput).



| field | type | required | note |
|---|---|---|---|
| `entity` | `id` | yes |  |



## Response
The route returns a card whose body is [WatchedIdentity](/concepts/watchedidentity). Every card ends with a foot that states the basis of each number, the scope of the call, and the time when the facts were true.

## Headers


| header | required | meaning |
|---|---|---|
| `Scale-Scope` | yes | the scope the call runs in: tenant/<id>, then /brand/<id>, then /strategy/<id> |
| `Scale-As-True-On` | no | the date the facts must have been true on; defaults to now |
| `Scale-As-Known-On` | no | the date the facts must have been known on; defaults to now |
| `Scale-Key` | no | for a change, the key made from the input; a repeat under the same key returns the unit held and writes nothing |



A caller needs the brand rung and a token with the act grant. The platform serves this route.

## Example
The example sends the smallest body that WatchInput allows. The build validates it against the schema of WatchInput.

<details class="wire"><summary>Example</summary>





```sh
curl -X POST https://api.scaleintelligence.co/v1/act/watch \
  -H "Scale-Key: $SCALE_KEY" -H "Scale-Scope: tenant/<id>" \
  -H "content-type: application/json" \
  -d '{ "entity": "…" }'
```




```typescript
import { client } from "@scale/sdk";
const answer = await client.act.watch({
    "entity": "…"
  });
// answer.body is a WatchedIdentity. answer.foot holds the basis, the scope and the time.
```




```python
import requests
answer = requests.post("https://api.scaleintelligence.co/v1/act/watch",
    headers={"Scale-Key": KEY, "Scale-Scope": "tenant/<id>"},
    json={
      "entity": "…"
    }).json()
```




```rust
let answer: Card = client.post("https://api.scaleintelligence.co/v1/act/watch")
    .header("Scale-Key", key).header("Scale-Scope", "tenant/<id>")
    .json(&WatchInput { /* the fields of the page */ }).send().await?.json().await?;
```




</details>

## MCP tool
The MCP tool `si.act.watch` takes the same input and returns the same card. The tool changes data and needs a grant. An MCP host that renders cards draws this card from `ui://scale-intelligence/cards/WatchedIdentity`. The [tool's page](/reference/tools/si-act-watch) describes it.