Music theory
Chords, scales, keys, modes, intervals, diatonic harmony, voice leading,
Roman-numeral analysis, key detection, substitutions and transposition —
all backed by tonal.
mcpFortyTwo
An MCP server that exposes music-theory analysis and MIDI generation as tools any MCP-capable client can call. Ask Claude (or any client that speaks Streamable HTTP MCP) to spell chords, detect keys, suggest reharmonizations, and render basslines, drum patterns, scales, arpeggios and full progressions as Standard MIDI Files — without leaving the chat.
What you get
Section titled “What you get”MIDI generation
Progressions, basslines, drum patterns, scales and arpeggios rendered as Standard MIDI File Type 1 (480 PPQ), returned base64-encoded so the host can decode straight into a DAW.
Knowledge graph
Postgres + Drizzle catalogue of curated progressions, modes, voicings and cadences, queryable through dedicated MCP tools.
Streamable HTTP
Stateless per-request transport — point any MCP client at /mcp and it
works. No long-running session state, no install.
Where to go next
Section titled “Where to go next” Getting started Connect Claude or another MCP client to the hosted server, or run mcpFortyTwo locally.
Configuration Environment variables, Postgres, Docker and the build pipeline.
Tool reference Auto-generated reference for every registered MCP tool — inputs, outputs and annotations.