Hosted, isolated Chromium sessions that report what they did, what they consumed, and what you were charged, line by line.
You keep the stop. A session you opened is a session you can end, from the portal or the API, and billable time ends according to the recorded session lifecycle. Settled charges come from an immutable ledger: we never reprice history.
A fetch tool returns the shell. A real browser runs the page's JavaScript, operates its controls, holds an authenticated profile between runs, reaches an application on your own machine through a tunnel, and leaves you a screenshot to check the work against. Each of those is a capability with limits, and the documentation states them.
Connect your agent, open a page, and keep a screenshot of the result.
If you are an agent: start with the API documentation; the shared skill download is coming soon.
Use the session and page IDs returned by the preceding commands.