André Hodeir here:
The Duke Ellington Orchestra recorded Concerto for Cootie, on March 15, 1940. It was especially written for his trumpet player, Cootie Williams. Later, Bob Russell wrote lyrics for the instrumental piece, and in 14 August 1943 Ellington did record the vocal version, featuring Al Hibbler as the singer, and apparently "it was a number one hit R&B chart for eight non-consecutive weeks and number six on the pop chart." This time the title of the song changed to Do Nothing Till You Hear From Me this and was recorded many times after that. Ella Fitzgerald, Louis Armstrong and Dinah Washington were among the people who sang in what was originally a concerto for trumpet wizard and master of mute plunger, Cootie Williams.
Concerto for Cootie is a masterpiece because every thing in it is pure; because it doesn't have that slight touch of softness which is enough to make so many other deserving records insipid. Concerto for Cootie is a masterpiece because the arranger and the soloist have refused in it any temptation to achieve an easy effect, and because the musical substance of it is so rich that not for one instant does the listener have an impression of monotony. Concerto for Cootie is a masterpiece because it shows the game being played for all it is worth, without anything's being held back, and because the game is won. We have here a real concerto in which the orchestra is not a simple background, in which the soloist doesn't waste his time in technical acrobatics or in gratuitous effects. Both have something to say, they say it well, and what they say is beautiful. Finally, Concerto for Cootie is a masterpiece because what the orchestra says is the indispensable complement to what the soloist says; because nothing is out of place or superfluous in it; and because the composition thus attains unity.
Concerto for Cootie should not be considered as an ordinary arrangement. Its unusual structure, the polish of its composition, the liberties with certain well-established rules that are taken in it, the refusal to improvise these characteristics are enough to place it rather on the level of original composition as this term is understood by artists of classical training.