Mozart played the piano and violin. However he is far more known for the works he composed during his life.
piano
As a composser, like most compossers, he played a instrument.
Violin and piano
Mozart was a prolific composer in classical period. He was an accomplished pianist and violinist. He showed his talents when he was three years old.
Mozart himself played violin and piano. He did not restrict his composition to any one instrument.
Mozart was known to play the harpsichord during his early years, particularly in the 1760s when he was a child prodigy. He composed several works for the instrument, including his early keyboard concertos and sonatas. The harpsichord was a prominent instrument in the Baroque period and remained in use during Mozart's time, influencing his style and compositions. However, as the piano became more popular, Mozart primarily focused on it in his later works.
Mozart was the first major composer for the clarinet, being a friend of Denner, the inventor of the instrument.
Mozart himself played violin and piano. He did not restrict his composition to any one instrument.
Mozart mastered piano, violin, and harpsichord
Mozart played many instruments including the piano, the violin, the viola, the organ, the harpsichord, the fiddle, and possibly several others including the clarinet and the trumpet.
The only composition of Mozart that contains the harp is the "Concerto in C for flute, harp, and orchestra. I guess any composer should at least know how an instrument works in order to compose for it!
Mozart played several, the one he liked best was the harpsichord.