Name the bride and make it clearly a shower
The word 'shower' is doing real work here: it tells guests to bring a gift and signals a relaxed, celebratory gathering rather than the wedding itself. Lead with the bride's name — 'a bridal shower honouring Eleanor Whitfield' — so there's no confusion about who's being celebrated, especially when guests are juggling several events in one wedding season.
Say who's hosting and how to RSVP
Showers are hosted by someone — a friend, a sister, the wedding party — and crediting them ('hosted with love by Claire and Anne') tells guests who to thank and who to reply to. Point the RSVP at the host, not the bride, and give a reply-by date; the host needs an accurate count for seating, food, and favors, and the bride shouldn't be fielding logistics for her own party.
Include the registry and any theme
Unlike a wedding invitation, where registry details are considered gift-grabby, a shower invitation is exactly the right place to note where the couple is registered — guests expect it and it makes their lives easier. If there's a theme, spell it out plainly ('kitchen shower,' 'recipes and wine,' 'her favourite bloom') so guests can shop and dress to match rather than guessing at the vibe.