chord-info

name	chord-info
description	Returns the notes and intervals of a named chord (e.g. Cmaj7 = C E G B). Calls the deterministic `ga_chord_info` MCP tool — never recall an answer from training data, since LLMs commonly flip enharmonics (Db vs C#) based on which source they saw.
triggers	["what is a chord","what is the chord","what chord is","what notes are in","notes in a","notes of a","spell a chord","spell the chord","chord notes","chord intervals","spell a c","spell a d","spell a e","spell a f","spell a g","spell an a","spell a b"]
license	internal
compatibility	{"agent-framework":">=1.0.0-preview","microsoft-extensions-ai":">=10.5.1"}
metadata	{"authoring-style":"tool-driven","origin":"third MCP-tool-driven canary; replaces direct C# ChordInfoSkill in the SKILL.md path","evidence-kinds":["tool_call"]}
allowed-tools	["ga_chord_info"]

Notes of a Chord

When a user asks for the notes / intervals / construction of a named chord, call the ga_chord_info MCP tool. Do NOT recall the notes from training knowledge — different sources spell the same chord differently (Bbm = Bb-Db-F vs Bb-C#-F) and the LLM will confidently produce wrong enharmonics for less-common keys.

Calling the tool

The tool takes one argument:

• chordSymbol — string, e.g. "C", "Cm", "Cmaj7", "F#dim", "Bbm7". Case-insensitive root letter; quality suffix uses the standard short forms below.

It returns a structured result:

• Symbol — chord symbol echoed back.
• Root — root note in canonical case (e.g. "F#").
• Quality — long form: "major", "minor", "diminished", "augmented", "dominant 7", "major 7", "minor 7", "diminished 7", "half-diminished".
• Notes — array of chord tones in ascending order.
• Intervals — interval names for each note (e.g. ["root", "major third", "perfect fifth"]).
• Error — non-null only when the input could not be parsed.

Supported quality suffixes

Symbol form	Quality returned
C, Cmaj, CM	"major"
Cm, Cmin	"minor"
Cdim	"diminished"
Caug	"augmented"
C7, Cdom7	"dominant 7"
Cmaj7, CM7	"major 7"
Cm7, Cmin7	"minor 7"
Cdim7	"diminished 7"
Cm7b5, Cmin7b5	"half-diminished"

Mapping user phrasings to arguments

• "What is a C major chord?" → chordSymbol="C" (or "Cmaj").
• "What notes are in Dm7?" → chordSymbol="Dm7".
• "Spell a B7 chord" → chordSymbol="B7".
• "Notes in an F minor chord" → chordSymbol="Fm".
• "What's in a Cmaj7?" → chordSymbol="Cmaj7".
• "Spell a B half-diminished" → chordSymbol="Bm7b5".
• "What's a C diminished 7th?" → chordSymbol="Cdim7".

Phrasing the answer

Use the Notes array verbatim, joined with – (en-dash) or commas. Mention the Quality and the Intervals for educational color. Example:

A Cmaj7 chord contains C – E – G – B (root, major third, perfect fifth, major seventh).

If Error is non-null, surface the message verbatim and ask the user to clarify.

When to ask for clarification

• User names a key rather than a chord (e.g. "what notes are in C major key" — vs "C major chord") → that's a scale-info question; defer to the scale-info skill, do NOT call ga_chord_info.
• User asks for a chord quality this tool doesn't support (sus2, sus4, 9th, 11th, 13th, slash chords, altered dominants like 7b5 or 7#9) — the tool will return an Error. Decline cleanly: "I can spell major / minor / diminished / augmented triads, major/minor/dominant sevenths, diminished sevenths (dim7) and half-diminished (m7b5). For altered or extended chords beyond those I'd need different tooling."

Out of scope

• Extended chords (9, 11, 13) — not yet supported.
• Altered / suspended / add chords (sus2, sus4, add9, 7b5, 7#9, etc.) — not supported. (m7b5 and dim7 ARE supported as of 2026-05-10.)
• Slash chords (C/E, Am/G) — not supported; pass just the upper chord and explain the bass note in prose.
• Chord identification from a note set ("what chord is C E G?") — not yet exposed; that would be a separate ga_chord_identify(notes) tool.

Cross-reference

• MCP tool: Common/GA.Business.ML/Agents/Mcp/ChordMcpTools.cs
• Tool tests: Tests/Common/GA.Business.ML.Tests/Unit/ChordMcpToolsTests.cs
• Legacy C# skill it replaces: Common/GA.Business.ML/Agents/Skills/ChordInfoSkill.cs (regex-driven, no LLM round-trip — kept for the deterministic fast path)