Shocking as it seems to me, that wikipedia page seems to be completely correct (and thorough, and well done).
I couldn't think of any reason why someone else would have done the arranging, so I would have thought Jobim. I also would have thought that Jobim played as well as sang on it, but that seems to be incorrect. Anyway, I dug up the following in a popsike listing (documenting an ebay sale of the record):
Technical Information
Artist: Tom Jobim & João Bosco
Tracks: "Águas de Março / Agnus Sei"
Recording Label: Independent (Disco de Bolso do Pasquim)
Company #: 280100
Year: 1972
Made in: Brazil
Sound Reproduction Format: STEREO
Pressing: 1st
Jacket Material: Laminated
Media: Vinyl Records 7"
Number of tracks: 02 tracks
Playing Speed: 33 1/3 RPM
Special features: The 20-page booklet with Graphics, Photos, Drawings, Interviews, Music scores, Technical information, Cartoons, texts, and Much more is included.
Personnel & Credits
Featuring (Musicians): Antônio Carlos Jobim (Vocal); Bebeto, Paulo Jobim, Franklin, Paulo Guimarães and Ratto (Flutes); Eduardo Athaíde (Acoustic Guitar); Novelli (Bass) and João Palma (Percussion), João Bosco (Acoustic Guitar and Vocal) Arranged by: Tom Jobim
Songs written by: Tom Jobim, João Bosco
Produced by: Sérgio Ricardo and Eduardo Athaíde
I have it somewhere (received a copy on cassette from another collector about 15 years ago... probably transferred it to MD or CDR, but hadn't played it for a long time). I don't really love it, actually. It sounds rushed, almost like it wasn't meant to be digested as seriously as later versions of it. On the other hand, the entry on the "Clube do Tom" website includes this: "the little difficulties he faced to sing the complicated lyrics in a fast tempo, instead of bothering the listener, contribute with a special charm to the importance of this historic première." To each their own.
I love the version with Elis; the Banda Nova version; and others, including this:
Not only did the cat swing, he looked like the Wizard of Oz!