THIRI Chord Intelligence — Music Theory MCP Server

Deterministic Music Theory for Claude, Cursor, and Autonomous AI Agents Large Language Models (LLMs) frequently hallucinate music theory, leading to incorrect…

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What it can do

  • Analyze Chord: Parse a chord into root, quality, intervals, and (with a key) roman numeral + function.
  • Resolve Chord: Resolve a chord to spelled notes, frequencies, MIDI, and recommended scales.
  • Generate Voicing: Instrument-ready voicing in a style; pass previousNotes for a voice-leading score.

What data it sees

Do you need an account

An API key from the service settings is required

Deterministic Music Theory for Claude, Cursor, and Autonomous AI Agents

Large Language Models (LLMs) frequently hallucinate music theory, leading to incorrect notes, false Roman numerals, and broken voice leading. THIRI solves this by providing a deterministic, mathematical music-theory engine (pitch-class-set theory over ℤ/12) directly to your AI.

It gives AI assistants precise, reproducible harmonic reasoning in milliseconds, allowing them to write correct musical scores, analyze progressions, and generate playable arrangements.

🎷 Key Features:

  • Chord Analysis (analyze_chord): Parse any symbol (e.g., Cmaj7/E, G7#11) to retrieve root, quality, intervals, Roman numerals, and diatonic or chromatic harmonic functions.
  • Note Resolution (resolve_chord): Resolve chord symbols to spelled notes (enharmonically correct), frequencies (Hz), MIDI numbers, and scale recommendations.
  • Voicing Engine (generate_voicing): Generate instrument-ready voicings (rootless, shell, triad, pad, drop-2, drop-3) and calculate voice-leading scores for transitions.
  • Reharmonization (reharmonize): Substitute progressions using classic jazz techniques, including Tritone Substitution, ii-V Insertion, Modal Interchange, Coltrane Changes, and Backdoor cadences.

Ideal for developers building AI music assistants, digital audio workstation (DAW) agents, educational theory tools, and automated composition workflows.

How to connect

How to connect THIRI Chord Intelligence — Music Theory MCP Server to Claude

The server address to paste into Claude settings:

https://thiri--dennison.run.tools

  1. Open Claude (claude.ai or the desktop app).
  2. Go to Settings → Connectors.
  3. Click Add custom connector.
  4. Paste the server address copied below into Remote MCP server URL and click Add.
  5. In a chat, click + → Connectors and switch the new connector on.

Custom connectors are available on Free, Pro, Max, Team and Enterprise plans (Free is limited to one). On Team and Enterprise an organization Owner adds the connector first under Organization settings → Connectors.

Authorization

After you click Add, a sign-in window for the service opens. Sign in with your own account and approve access. Claude never sees your password.

How to connect THIRI Chord Intelligence — Music Theory MCP Server to ChatGPT

The server address to paste into ChatGPT settings:

https://thiri--dennison.run.tools

  1. Open ChatGPT in a browser (chatgpt.com). A Plus, Pro, Business, Enterprise or Edu plan is required.
  2. Turn on developer mode once: Settings → Apps → Advanced settings → Developer mode.
  3. Open Settings → Connectors and click Create.
  4. Fill in the form: Name (anything), Description (one line about what the service does), MCP server URL (copy it below).
  5. Under Authentication choose OAuth if the service requires sign-in, otherwise None. Click Create.
  6. In a new chat open + → Apps/Connectors and enable the connector.

OpenAI has renamed this section before (Connectors → Apps/Plugins). If the label differs, search settings for "developer mode". On Business/Enterprise workspaces an admin must allow custom connectors first.

Authorization

On first use ChatGPT opens the service's sign-in window. Sign in and approve access.

How to connect THIRI Chord Intelligence — Music Theory MCP Server to Cursor

The server address to paste into Cursor settings:

https://thiri--dennison.run.tools

Fastest: click Open in Cursor below and confirm the prompt.

Manually:

  1. In Cursor open Settings → Cursor Settings → MCP and click Add new global MCP server.
  2. Paste the JSON copied below into ~/.cursor/mcp.json (per project: .cursor/mcp.json in the repo root).
  3. Save the file. The server appears in the MCP list; authorize it there if asked.

Authorization

If the service needs sign-in, an authorize button appears next to the server in the MCP list.

Server tool list (4)

Raw names from tools/list. Only developers need these.

analyze_chordParse a chord into root, quality, intervals, and (with a key) roman numeral + function.
resolve_chordResolve a chord to spelled notes, frequencies, MIDI, and recommended scales.
generate_voicingInstrument-ready voicing in a style; pass previousNotes for a voice-leading score.
reharmonizeReharmonize a progression. Techniques: tritone_sub, ii_v_insertion, modal_interchange, diminished_passing, secondary_dominant, chain_of_dominants, coltrane_changes, backdoor (or auto).