# THIRI Chord Intelligence

Computes exact music theory, voicings, and reharmonizations for coding agents. Useful whenever your assistant needs reliable chord logic without LLM hallucinations.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI · ★ 12
- Author: BluesPrince
- License: not stated · policy=link-only · description only; the file stays with the author
- Source: https://github.com/BluesPrince/thiri-mcp
- Updated: 2026-10-19
- HTML: https://affpapa.org/en/nevibecode/mcp/thiri-chord-intelligence

## What it does

Language models frequently hallucinate chord tones and awkward voice leading. THIRI avoids statistical guessing by evaluating pitch-class sets mathematically over ℤ/12. The calculation stays deterministic. Available tools include `analyze_chord` for harmonic functions and `reharmonize` with 8 standard methods, including tritone substitutions and Coltrane changes.

The `generate_voicing` tool builds voicings such as rootless forms while scoring transitions against previous chords. Through `conduct_band`, the model splits natural language song prompts into instrument tracks. Audio rendering runs remotely through `POST /v2/render`, so local Csound installations are unnecessary.

You need an API key from `build.thiri.ai/keys` to run requests. While the hosted HTTP endpoint handles chord calculations, local sound playback requires running the companion package via stdio.

## Requirements
- Needs: Node.js (commands run via npx)
- Remote server: `https://mcp.thiri.ai/mcp`
- Environment variables: `THIRI_API_KEY` — keys and tokens: ask the human for the values, never commit them or put them in shared files.

## Install

### Claude Code (native platform)

1. **Platform CLI: remote server**
```bash
claude mcp add --transport http chord-intelligence https://mcp.thiri.ai/mcp
```

2. **Platform CLI**
```bash
claude mcp add --env THIRI_API_KEY=<THIRI_API_KEY> --transport stdio thiri-chord-intelligence -- npx -y @bluesprincemedia/thiri-mcp
```
Replace <…> with your own values

### Codex

1. **Platform CLI: remote server**
```bash
codex mcp add thiri-chord-intelligence --url https://mcp.thiri.ai/mcp
```

2. **Platform CLI**
```bash
codex mcp add thiri-chord-intelligence --env THIRI_API_KEY=<THIRI_API_KEY> -- npx -y @bluesprincemedia/thiri-mcp
```
Replace <…> with your own values

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "thiri-chord-intelligence": {
            "url": "https://mcp.thiri.ai/mcp"
        }
    }
}
```
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "thiri-chord-intelligence": {
            "command": "npx",
            "args": [
                "-y",
                "@bluesprincemedia/thiri-mcp"
            ],
            "env": {
                "THIRI_API_KEY": "<THIRI_API_KEY>"
            }
        }
    }
}
```
Replace <…> with your own values

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "thiri-chord-intelligence": {
            "type": "http",
            "url": "https://mcp.thiri.ai/mcp"
        }
    }
}
```
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "thiri-chord-intelligence": {
            "type": "stdio",
            "command": "npx",
            "args": [
                "-y",
                "@bluesprincemedia/thiri-mcp"
            ],
            "env": {
                "THIRI_API_KEY": "<THIRI_API_KEY>"
            }
        }
    }
}
```
Replace <…> with your own values

### Gemini CLI

1. **Platform CLI: remote server**
```bash
gemini mcp add -t http thiri-chord-intelligence https://mcp.thiri.ai/mcp
```

2. **Platform CLI**
```bash
gemini mcp add -e THIRI_API_KEY=<THIRI_API_KEY> thiri-chord-intelligence npx -y @bluesprincemedia/thiri-mcp
```
Replace <…> with your own values

## When to use it
- calculate roman numerals and harmonic functions without errors
- spell chord pitches and MIDI notes accurately
- reharmonize progressions using tritone substitutions or Coltrane changes
- turn natural language song descriptions into instrument lanes

## Example prompts
- Analyze the chord progression Dm7 G7 Cmaj7 in the key of C.
- Generate a rootless voicing for Cmaj7 and evaluate voice leading into Dm7.
- Apply Coltrane changes to reharmonize Dm7 G7 Cmaj7.

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