Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add GuitarAlchemist/ga --skill intervalgit clone --depth 1 https://github.com/GuitarAlchemist/gaWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/guitaralchemist/ga/interval)<a href="https://agentmods.dev/skills/guitaralchemist/ga/interval"><img src="https://agentmods.dev/badge/skills/guitaralchemist/ga/interval/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/guitaralchemist/ga/interval"><img src="https://agentmods.dev/badge/skills/guitaralchemist/ga/interval.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00042 | $0.01014 |
| Opus 5.5 | $0.00017 | $0.00406 |
| Sonnet 5.5 | $0.00008 | $0.00203 |
| Haiku 4.5 | $0.00004 | $0.00101 |
Grade A, and why
interval scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 76 lines — stays where its author put it; the contents beside it link to each section on GitHub.
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 theSemitonesfield 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
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 76 lines · 42 tokens per session scan A d16cdfd31ad9
interval is a skill published in the GitHub repository GuitarAlchemist/ga (2 stars, last pushed yesterday), licensed MIT. It adds 42 tokens to every session and 1,014 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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