I'm sending my second draft of the novel out to beta readers this month, so I thought I'd ask the forum for some help with this query letter. Any and all feedback is welcome. Thanks!
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Dear [Agent],
On a bright summer day, a mysterious teenager appears in the ordinary town of Remington. Thomas Lysander calls himself an Ambassador to the Waking World. His job is stealing people away—never without their permission, of course—to the dreamsea, the collection of worlds that we visit when we sleep. He’s now offering this opportunity to Edgar and Rosalind Lucas.
What Edgar and Rosa hope to find is their runaway brother James, who’s been missing for two years. Tom says that their brother has been in the dreamsea all along, making himself a newself: the hero, the Great César Lucas. Their brother made history by standing against the Rust Golem, otherwise known as the Iron Ghost, the Hunter-Seeker, the Bloodsound: a fearsome shadow made of haunted metal with smoldering indigo eyes. Hero or not, their brother lost that battle.
If they’re ever to see their brother again, Eddie and Rosa must master the rules of unusual dreamscapes, from the law-obsessed city of Nomos to the crowded Chatterworld to the nightmare planet where James finally disappeared. The enigmatic Tom Lysander serves as their tour guide, but why is he obsessed with finding the Great César in the first place? It seems that everyone who can’t find their brother is following them—including the Rust Golem itself.
DREAMSEA is a YA urban fantasy, complete at 102,000 words. I’m sending this query to you because [xxx]. Written in the tradition of books like THE PHANTOM TOLLBOOTH and A WRINKLE IN TIME, this novel explores multiple worlds, each with its own mysteries and dangers.
Thank you for considering my work! I appreciate your time.
Sincerely,
[name, address, email, website]
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Thanks in advance for any and all comments. If you have a query letter that I haven't commented on, let me know and I'll be more than happy to return the favor.

Best,
tomlysander