PlayByKey Music Theory MCP server

Read from the package source without running it. The installed server may list more.

• build_note_map

  Returns structured per-note data for a scale: note name, scale degree (1-based), and semitone offset from root.

• get_available_inversions

  Returns the valid inversion numbers for a chord type, based on its note count.

• get_bebop_scale_notes

  Returns the eight notes of a bebop scale variant for a root - a diatonic scale plus one chromatic passing tone.

• get_chord_by_degree

  Returns the diatonic chord at a specific scale degree (1-7) for a key/mode.

• get_chord_inversion

  Reorders a chord's notes so the given inversion's chord tone is lowest.

• get_chord_notes

  Returns the notes of a chord given a root and chord type.

• get_circle_of_fifths

  Returns all 12 chromatic notes in ascending-fifths order starting from C.

• get_diatonic_chords

  Returns the 7 diatonic triads for a key/mode, one per scale degree, in degree order.

• get_enharmonic_labels

  Returns combined sharp/flat display labels for a list of sharp-spelled notes, e.g. ["C#", "D"] -> ["Db/C#", "D"]. Natural notes are unaffected. Input must already be sharp-spelled - use get_sharps first if you have flat-spelled notes.

• get_flats

  Respells a list of sharp-spelled notes as flats, e.g. ["C#", "D"] -> ["Db", "D"]. Natural notes are unaffected. Input must already be sharp-spelled (as returned by get_scale_notes, get_mode_notes, etc.) - use get_sharps first if you have flat-spelled notes.

• get_harmonic_minor_mode_notes

  Returns the seven notes of a harmonic minor mode for a root.

• get_key_signature

  Returns the sharp or flat count for a given key, treated as a major-key tonic (minor-key signatures are not exposed by this tool).

• get_melodic_minor_mode_notes

  Returns the seven notes of a melodic minor mode for a root.

• get_melodic_minor_notes

  Returns the seven notes of the ascending melodic minor scale for a root.

• get_modal_root

  Returns the root note of a mode within a given parent (Ionian/major) key.

• get_mode_info

  Returns display metadata for a mode: name, scale degree, and characteristic description.

• get_mode_notes

  Returns the 7 notes of a diatonic mode for a given root note.

• get_parent_scale_modes

  Returns all 7 modal rotations of the parent key for a given root and mode.

• get_progression_in_key

  Renders a named catalog progression as chords in a given key, in order.

• get_relative_major

  Returns the relative major root for a minor key.

• get_relative_minor

  Returns the relative minor root for a major key.

• get_roman_numeral

  Returns the roman numeral for a scale degree in a mode - case and suffix reflect diatonic triad quality.

• get_scale_degree

  Returns the 1-based scale degree of a note within a root + scale type, or null if the note is not in the scale.

• get_scale_notes

  Returns the notes of a scale by type. Covers all ScaleType values: major, blues, pentatonic-major, pentatonic-minor, harmonic-minor, melodic-minor, chromatic.

• get_semitone_distance

  Returns the ascending semitone distance between two notes (0-11).

• get_sharps

  Respells a list of notes to canonical sharp spelling, e.g. ["Db", "C#", "D"] -> ["C#", "C#", "D"]. Most tools accept flat-spelled input directly, but get_flats and get_enharmonic_labels require sharp-spelled input - use this to normalize flat-spelled notes before calling those two.

• is_note_in_scale

  Returns true if the given note is present in the specified root + scale type, false otherwise.

• midi_to_note

  Returns the note and octave for a given MIDI note number - the inverse of note_to_midi.

• note_to_frequency

  Returns the frequency in Hz for a note at a given octave, equal temperament, A4 = 440Hz.

• note_to_midi

  Returns the MIDI note number for a note at a given octave, using scientific pitch notation (C4 = middle C = MIDI 60).

• resolve_interval

  Returns the from-note and to-note for a named interval within a root context.

• transpose

  Transposes a set of notes from one key to another by the semitone distance between the two roots.

• Code scan3 source files scanned20/25
• –Live reliabilityno gateway calls yet and no remote to proben/a
• –Tool poisoningtools not inspected (local package is not executed); not countedn/a
• Auth qualitylocal package, no credentials required12/15
• Maintenancelast push 10 days ago15/15
• Maintainer identitynamespace and repository owner differ; GitHub account older than a year6/10

Safety score

82/100

higher than 63% of 48,255 servers

Tools

32

the typical server has 7

Tools that change things

0%

typical: 0%. Fewer write tools means less an agent can break

GitHub stars

1

more than 65% of 28,688 servers

Downloads a week

76

more than 56% of 12,191 servers with a package

PlayByKey Music Theory: common questions

Is PlayByKey Music Theory MCP server safe?

Mostly: it is graded B (82/100). Read the PlayByKey Music Theory safety report

How do I install PlayByKey Music Theory?

It runs on your machine. Copy the Claude Code, Cursor, VS Code or Claude Desktop config from the install section.

Does PlayByKey Music Theory need an API key?

Not as far as the registry entry and our scan can tell: no credentials are declared or required.

Is PlayByKey Music Theory maintained?

The last commit was 51 days ago (2026-09-14). The latest release is v1.6.0.

How does PlayByKey Music Theory compare with other MCP servers?

safety score 82/100 (higher than 63% of 48,255 servers); tools 32 (the typical server has 7); tools that change things 0% (typical: 0%. Fewer write tools means less an agent can break). Full comparison.