# update

URL: /business/nouns/meter/update · Id: `verb:Meter.update` · Call: `await $.Meter.update({ … })` (SDK) or the `do` tool at `https://api.sb/mcp`. Inputs says what to pass, Outputs what returns, When it waits who approves.

> Changes the given properties of a Meter.

Update changes the given properties of a [Meter](/business/nouns/meter). It is inherited: every [Noun](/business/nouns/noun) has `get`, `list`, `create`, `update` and `delete`.

## Inputs
| Input | Type | Required | Description |
| --- | --- | --- | --- |
| `id` | `string` | Yes | The id of the Meter. |
| `unit` | `string` | No | What it counts, such as calls or tokens. |
| `of` | `string` | No | The declared Event the Meter counts. |
| `aggregation` | `string` | No | How counted Events combine over the window: a sum of a value, a count, or the last value. |
| `window` | `string` | No | The period usage accrues over before it bills, such as a month. |

## Outputs
| Output | Type | Required | Description |
| --- | --- | --- | --- |
| `meter` | [Meter](/business/nouns/meter) | Yes | The Meter. |

## Effects
- Emits `Meter.updated`.
- Two-way: `try`, `send`, `do`.

## Refuses when
| Check | Error | Fix | Then call |
| --- | --- | --- | --- |
| The key is valid, but its scopes do not allow this operation. | [`forbidden`](/code/api/errors/forbidden) | Use a key whose scopes cover the operation, or ask an owner of the namespace to grant them. | [Meter.update](/business/nouns/meter/update) |

## When it waits
| Gate | Default |
| --- | --- |
| Decision class | Low: two-way, nothing at stake |
| [Delay window](/systems/trust-and-governance/controls/one-way-windows) | None: it runs once review passes. |
| Limit | The call [Limit](/business/nouns/limit) of the [Permission](/business/nouns/permission) it runs under. |
| Over the Limit | It waits `pending` for an [Approval](/business/nouns/approval) from the [Founder](/agents/founding/founder). Approved, it runs; refused, it ends `refused` with [`limit-exceeded`](/code/api/errors/limit-exceeded); unanswered by its deadline, it ends `canceled`. |

## Example

**Ask**

```text
Change the latest meter.
```

**API**

```bash
curl -X PATCH https://api.sb/petpantry.shop/meters/meter_1 \
  -H "Authorization: Bearer $STARTUP_BUILDER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"unit":"call"}'
```

```json
{
  "api": "https://api.sb/petpantry.shop",
  "meter": {
    "$id": "https://api.sb/petpantry.shop/meters/meter_1",
    "$type": "Meter",
    "unit": "call",
    "of": "Reminder.sent",
    "aggregation": "sum",
    "window": "month"
  },
  "action": {
    "$id": "https://api.sb/petpantry.shop/actions/action_1",
    "operation": "Meter.update",
    "status": "done"
  },
  "links": {
    "self": "https://api.sb/petpantry.shop/actions/action_1"
  }
}
```

**SDK**

```ts
import { $ } from 'startup-builder'

const meter = await $.Meter.update({ id: 'meter_1', unit: 'call' })
```

**CLI**

```bash
npx startup-builder do Meter.update --json '{"id":"meter_1","unit":"call"}'
```

**MCP**

```json
{
  "name": "do",
  "arguments": {
    "code": "return await $.Meter.update({ id: 'meter_1', unit: 'call' })"
  }
}
```