PlayByKey Music Theory README
The full upstream README, mirrored here for reference. Install config, tool schemas, adoption signals, and an original overview live on the PlayByKey Music Theory listing page.
Developer Tools
Packages for PlayByKey - see the table below for what's here.
- npm: npmjs.com/package/@playbykey/theory
- Documentation: theory-engine.docs.playbykey.com - interactive playgrounds
- Changelog: GitHub Releases
Install
Quickstart and API examples: packages/theory/README.md
Why @playbykey/theory
- Foundation music theory engine: music theory as code. Modes, keys, intervals, and scale relationships resolved deterministically; one source of truth every app, notation tool, or AI agent can build on.
- Zero dependencies: no transitive baggage; safe for agents, edge runtimes, and tight bundles
- Strictly typed: every function's types exported alongside it, no
any - Agent-ready: copy-paste LLM context prompt and interactive docs
- Sharps-only notation: one canonical spelling per note (
C#, notDb) keeps theNotetype safe and unambiguous. Flats are fully supported for both input (parseNote/parseNoteTokenacceptDb,Eb,Gb,Ab,Bb) and output (getFlats/getEnharmonicLabels), without extendingNoteitself.
Packages
| Package | Description | Links |
|---|---|---|
@playbykey/theory | Zero-dependency music theory engine - scales, modes, intervals, chords, progressions, key relationships | npm · docs · changelog |
@playbykey/theory-mcp | MCP server that exposes the theory engine as AI-callable tools | npm · README |
theory-docs | Starlight documentation site (private workspace package) | live site · README |
License
MIT for the repository tooling and @playbykey/theory. See LICENSE.
Individual packages may declare their own license in their package.json.