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

# Usage & Metering

> Track per-key tool usage: current-period units, lifetime totals, and a per-tool breakdown.

Every tool call, whether it comes through the [Tools API](/api-reference/overview) or the [MCP server](/mcp/overview), is metered against the key that made it. You can review usage per key in the app.

## Where to find it

In the app, open the profile menu, choose **MCP Keys**, then expand a key's **Usage** panel.

## What's tracked

<ResponseField name="current_period" type="string | null">
  The current billing period, formatted `YYYYMM`, for example `202607`.
</ResponseField>

<ResponseField name="current_period_units" type="number">
  Units consumed by this key in the current period.
</ResponseField>

<ResponseField name="total_calls" type="number">
  Lifetime number of tool calls made with this key.
</ResponseField>

<ResponseField name="total_units" type="number">
  Lifetime units consumed by this key.
</ResponseField>

<ResponseField name="by_tool" type="array">
  Per-tool breakdown. Each entry is `{ tool, calls, units }`: the tool name, how many times it was called, and the units it consumed.
</ResponseField>

### Example

```json theme={null}
{
  "key_id": "b3f1c2a4",
  "current_period": "202607",
  "current_period_units": 128,
  "total_calls": 5140,
  "total_units": 6021,
  "by_tool": [
    { "tool": "get_wallet_portfolio_breakdown", "calls": 2100, "units": 2100 },
    { "tool": "analyze_transaction", "calls": 820, "units": 1640 }
  ]
}
```

## Notes

* **Units versus calls**: a call is one tool invocation; units are the metered cost of that call. Some tools cost more than one unit.
* **Per surface**: the Tools API and the MCP server are metered on independent per-key windows.
* **Owner-scoped**: you can only see usage for your own keys.

<Tip>
  Use a separate key per workload, such as a bot, a notebook, and a backend, so the per-key and per-tool breakdown tells you exactly where your usage is going.
</Tip>