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 key-identificationgit 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/key-identification)<a href="https://agentmods.dev/skills/guitaralchemist/ga/key-identification"><img src="https://agentmods.dev/badge/skills/guitaralchemist/ga/key-identification/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/key-identification"><img src="https://agentmods.dev/badge/skills/guitaralchemist/ga/key-identification.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 | $0.00059 | $0.01169 |
| Opus 5 | $0.00030 | $0.00584 |
| Sonnet 5 | $0.00012 | $0.00234 |
| Haiku 4.5 | $0.00006 | $0.00117 |
Grade A, and why
key-identification 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 9d 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 — 90 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Key Identification
When a user asks what key a chord progression is in, call ga_key_identify. Do NOT analyze the progression from training knowledge — the diatonic-set match is pitch-class arithmetic and the LLM is unreliable at it.
Calling the tool
The tool takes one argument:
query— string. Either a bare chord list ("C Am F G") or the user's full question ("what key is C Am F G in?"). The tool extracts chord symbols from prose.
It returns a structured result:
RecognizedChords— string array, what the parser actually saw (useful for catching typos).TopCandidates— array ofKeyCandidateInfo. Keys tied at the highest match count.PartialMatches— up to 3 partial-match keys ranked behind the top set.TotalChords— total chords parsed.Error— non-null when no chords parsed or no candidates matched.
Each KeyCandidateInfo has:
Key— canonical key name (e.g."C major","A minor").RelativeKey— name of the relative pair.MatchCount/TotalChords— N of M chords are diatonic in this key.DiatonicSet— the seven diatonic chords (Ithroughvii°) in order.
Phrasing the answer
Your job is to explain the key choice in guitarist-friendly language. Use the structured tool result; do NOT add analysis the tool didn't compute.
Single top candidate
When TopCandidates has exactly one entry: lead with the key name and the match score, give the Roman numeral function of each input chord, and mention the diatonic set.
The progression
Dm G Cis in C major (3/3 chords diatonic). In C major: Dm = ii, G = V, C = I — a classic ii-V-I cadence. The diatonic chords of C major are C – Dm – Em – F – G – Am – B°.
Tied candidates (relative-pair ambiguity)
When TopCandidates has multiple entries (almost always 2 — the relative major/minor pair share a diatonic set): name both, then explain how to distinguish them by ear.
The progression
C Am F Gfits C major AND A minor equally — both contain all four chords. To tell them apart, listen for the tonic: if the progression keeps resolving to C as home, it's C major; if Am feels like home, it's A minor. The relative-key pair shares the diatonic set C – Dm – Em – F – G – Am – B°.
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.
- 9d ago First seen · 90 lines · 59 tokens per session scan A 8685d1122819
key-identification is a skill published in the GitHub repository GuitarAlchemist/ga (2 stars, last pushed today), licensed MIT. It adds 59 tokens to every session and 1,169 once invoked, about $0.0003 per session on Opus 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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