# Stopwatch

- Human page: https://happytails.ai/en/date-time-tools/stopwatch/
- Markdown: https://happytails.ai/en/date-time-tools/stopwatch.md
- Structured JSON: https://happytails.ai/agents/en/date-time-tools/stopwatch/index.json
- Visibility: public

## Tool capabilities

| Property | Value |
| --- | --- |
| Tool ID | `stopwatch` |
| Category | date-time-tools |
| Implementation | Registered implementation. Registration alone is not a production-quality guarantee. |
| Browser execution | Use the visible action or interactive controls. |
| Browser processing | Browser; see tool notes for network behavior. |
| HTTP API | Not callable through HTTP. |
| Browser-agent interface | No callable WebMCP interface. |

### Implementation notes

Elapsed time uses the browser’s monotonic clock.

### Inputs and settings

No free-text input is required. Use the file inputs and/or settings below.

No additional settings are declared for this tool.

### Planning specification

Lap times, keyboard controls and monotonic elapsed time.

This describes intended requirements. Use the implementation notes, interface schema and observed output to determine current support.

### Complete machine-readable capability record

```json
{
  "id": "stopwatch",
  "category": "date-time-tools",
  "built": true,
  "requirements": "Lap times, keyboard controls and monotonic elapsed time.",
  "implementation": {
    "fields": [],
    "input": false,
    "note": "Elapsed time uses the browser’s monotonic clock.",
    "experience": {
      "automatic": false,
      "single": false,
      "label": "Your text",
      "placeholder": "Type or paste your input…",
      "help": "Up to 1,000,000 characters. Review the settings before running.",
      "action": null
    },
    "mode": "explicit",
    "interactive": true
  },
  "execution": "Browser interface",
  "api": null,
  "browser_agent": {
    "supported": false,
    "name": null,
    "discovery": "WebMCP on the human page in a supporting browser",
    "verification": "See audit/API-AUDIT.md; availability is not verification"
  }
}
```

## Page guide

Measure elapsed time and take lap readings.

## Useful next steps

- [Timer](https://happytails.ai/en/date-time-tools/timer/): Set a countdown in seconds. ([Markdown](https://happytails.ai/en/date-time-tools/timer.md))

## How to use Stopwatch

1. Choose Start / pause to begin.
2. Choose Lap to read the current elapsed time, or Start / pause to pause.
3. Choose Reset when you want to start a fresh session.

## What to expect

Measure elapsed time and take lap readings. Start or pause the clock with the same button. Reset stops the clock and returns it to zero. Keep the page open to preserve the current session.