A guitarist can hold a familiar C-major shape while the audience hears a D-major chord. With a full capo at the second fret on a guitar in standard tuning, the sounding pitch rises by two semitones even though the relative fingering remains familiar.
Name the shape and the sound separately
A capo acts as a movable stopping point across the strings. Each fret higher raises the pitch by one semitone. This makes it useful when a player wants to keep open-position shapes while moving a song into another key.
Consider an illustrative progression using G, C and D shapes with a capo at the second fret. The sounding chords are A, D and E. Telling a keyboard player only “G, C, D” would send them towards the wrong harmony unless they knew you were naming shapes rather than concert pitch.
Write a chart that another musician can use
At the top of a guitar chart, record the tuning and capo position. State whether the chord names refer to shapes or sounding chords. If several instruments are involved, providing the sounding key removes an avoidable rehearsal conversation.
For your own practice, play one chord without the capo, then move the capo and identify the new chord by counting semitones. Listen to the result as well as naming it. This connects the visual position to the musical change.
Check the instrument after fitting it
Fit the capo according to its design, close enough behind the fret to stop the strings cleanly without sitting on top of it. Check tuning and listen for buzzing or muted strings. Excess pressure or an uneven fit can affect the sound, so do not assume the device makes every string correct automatically.
A capo can make a chord shape convenient, but it does not decide the best singing range. Try the passage with the vocalist and agree on the sounding key before printing the final chart.