The phrase "a libretto that" is correct and usable in written English.
It can be used when referring to a specific libretto in a context where you want to describe or elaborate on it further.
Example: "The opera features a libretto that beautifully captures the essence of the original novel."
Alternatives: "a text that" or "a script that".
Frustrated, Zemlinsky searched for a libretto that would capture the public's attention.
Accordingly, they came up with a libretto that cast Printemps's life in terms of her love affair with the public.
A current of self-denial runs through "Caroline," from a libretto that refuses to sentimentalize its heroine to its deliberately fragmented score that avoids anthems of uplift.
As Mr. Jenkins explains in the foreword to the published libretto, he sought a story that had relevance and depth; a libretto that would invite music; a musical score that "sang," by a composer who "walked the narrow line" between the post-Romantic styles that have become fashionable and "a harder-edged, more 20th-century sound".
He avoided opera for most of his career because, as he put it in 1978, "American opera is a novelty, to be played once and that's all, even when they're good pieces," and because he doubted he could find a libretto that interested him.
On each occasion, after a few months' pause, Gilbert responded with a libretto that met Sullivan's objections, and the partnership continued successfully.
A few stray plot strands and a quizzical ending aside, it's a deft libretto that balances zany double-entendres with plainspoken poetry, mocking exaggeration with empathetic realism.
That's a shame, as it features gorgeous music, complex characters and a knowing libretto that treats the story of Jason's quest for the Golden Fleece with a mixture of emotion and absurdity.
Mozart had no say in the matter of the story; it was an adaptation of a 1734 Metastasio libretto that had already been set by a few dozen composers.
He has assembled a spectacularly idiosyncratic libretto that draws not only on Dante's epic tour of hell, purgatory and paradise, but also on the Bible (fragments from Psalm 107 and Song of Songs), works by the 17th-century Dutch poet Joost van den Vondel and other sources.
Mr. Gréaud commissioned an original opera score and libretto that were recorded by the Orchestre Philharmonique de Radio France.
