interval

name	interval
description	Computes the simple interval between two named pitches (e.g. C to G is a perfect fifth). Calls the deterministic `ga_interval_compute` MCP tool — never recall an answer from training data.
triggers	["interval between","interval from","what is the interval","distance from","distance between","how many semitones","semitones from","semitones between"]
license	internal
compatibility	{"agent-framework":">=1.0.0-preview","microsoft-extensions-ai":">=10.5.1"}
metadata	{"authoring-style":"tool-driven","origin":"first MCP-tool-driven canary; replaces direct C# IntervalSkill in the SKILL.md path","evidence-kinds":["tool_call"]}
allowed-tools	["ga_interval_compute"]

Interval Between Two Notes

When a user asks for the interval, distance, or semitone count between two named pitches, you MUST call the ga_interval_compute MCP tool. Do NOT compute the answer from training knowledge — the tool is deterministic and the model is not.

Calling the tool

The tool takes two arguments:

• lowerNote — string, e.g. "C", "F#", "Bb". Case-insensitive.
• upperNote — string, same notation.

The tool returns a structured result with these fields:

• Name — short interval name (e.g. "P5", "m3").
• Quality — long form: "perfect", "major", "minor", "augmented", "diminished".
• Size — long form: "unison", "second", "third", ..., "octave".
• Semitones — integer 0–12.
• Error — non-null only when input could not be parsed.

Picking the lower / upper note

Map the user's phrasing to argument order:

• "interval from C to G" → lowerNote="C", upperNote="G".
• "interval between C and G" → same as above; the first-mentioned note is the lower.
• "distance from F# to D" → lowerNote="F#", upperNote="D". Pass both in order even when the lower is alphabetically later — the tool computes the simple interval correctly.
• "how many semitones from A to E" → lowerNote="A", upperNote="E". Read out the Semitones field to answer.

Phrasing the answer

Use the tool's Quality and Size words verbatim, then quote the short Name and Semitones count. Example:

From C to G is a perfect fifth (P5, 7 semitones).

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

When to ask for clarification

If the user provides only one note, or names a chord rather than two notes (e.g. "interval of A", "what's the interval in a Cmaj7"), do NOT call the tool with placeholder values — ask for the missing pitch first. Example response: "Could you give me both notes? E.g. 'interval from C to G' or 'distance between F# and A'."

Out of scope

• Compound intervals (9th, 13th, etc.) — the tool returns the simple interval. If the user asks "interval from C to high D", call the tool with C and D (which gives a major second), then in the answer flag the octave assumption explicitly: "I'm treating 'high D' as D one octave above C, so the compound interval is a major ninth (M2 plus an octave). If you meant a different D, let me know." Always state which D you assumed.
• Microtonal / just-intonation intervals — the tool only handles the standard 12-tone system. Decline cleanly: "This skill computes intervals in 12-TET only; for cents-based answers I'd need different tooling."

Cross-reference

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