No, context is not added by default. With third party libraries like anyhow, it's possible to add context[0] before `?` operator in human-readable or machine-readable form:

    a_method().context("Failed to complete the work")?;
    a_method().context(FailedToCompleteTheWork)?;

[0]: https://docs.rs/anyhow/latest/anyhow/trait.Context.html

That depends on the type you use to represent errors. A more "fancy" error type will allow you to add context / backtraces / whatever you want, while a simpler error type, for example just an error code, does not. (The error type is the E in Result<T, E>).