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

# Options

> Everything watch() accepts, what each default is, and what happens when you leave it out.

```ts theme={null}
watch(server, {
  key: process.env.MCPULSE_KEY ?? "",
  debug: true,
});
```

| Option     | Type      | Default         |                                                                              |
| ---------- | --------- | --------------- | ---------------------------------------------------------------------------- |
| `key`      | `string`  | —               | **Required.** The ingest key, `mp_live_…`. Without one the SDK does nothing. |
| `debug`    | `boolean` | `false`         | Log what is sent, and why a send failed, to **stderr**.                      |
| `enabled`  | `boolean` | `true`          | Set `false` to make `watch()` a no-op. Useful in tests and CI.               |
| `endpoint` | `string`  | The MCPulse API | Where payloads go. Only for pointing at a local API while developing.        |

## key

Trimmed on the way in. An **empty key turns the SDK off** regardless of `enabled` — a server started without its key configured should be silent, not a source of 401s on every flush.

There is no fallback to an environment variable inside the package. Read the variable yourself and pass it, so the source of the key is visible in your own code.

## debug

Writes to stderr, never stdout, because on a [stdio server](/sdk/stdio) stdout is the transport.

Turn it on when nothing is arriving. See [Troubleshooting](/sdk/troubleshooting) for what each line means.

## enabled

`enabled: false` skips instrumentation entirely. The server is returned untouched.

```ts theme={null}
watch(server, {
  key: process.env.MCPULSE_KEY ?? "",
  enabled: process.env.NODE_ENV === "production",
});
```

## endpoint

<Warning>
  Leave this alone in production. MCPulse is not self-hosted, so there is nowhere else to point — and because the SDK never throws and drops batches it cannot send, a wrong endpoint means you install, wrap, see no error at all, and simply never appear in your dashboard.
</Warning>

Its one real use is [local development](/guides/local-development), pointing at an API running on your own machine:

```ts theme={null}
watch(server, {
  key: process.env.MCPULSE_KEY ?? "",
  endpoint: "http://localhost:3000",
});
```

A trailing slash is stripped for you.

## Buffering constants

Not options — they are fixed, and the reasoning is in [What is sent](/sdk/what-is-sent).

|                    |                                     |
| ------------------ | ----------------------------------- |
| Flush at           | 30 payloads                         |
| Flush every        | 5 seconds                           |
| Buffer cap         | 1000 payloads, oldest dropped first |
| Exit flush timeout | 1 second, best effort               |