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 oaustegard/claude-skills --skill listening-to-musicgit clone --depth 1 https://github.com/oaustegard/claude-skillsWrote 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/oaustegard/claude-skills/listening-to-music)<a href="https://agentmods.dev/skills/oaustegard/claude-skills/listening-to-music"><img src="https://agentmods.dev/badge/skills/oaustegard/claude-skills/listening-to-music/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/oaustegard/claude-skills/listening-to-music"><img src="https://agentmods.dev/badge/skills/oaustegard/claude-skills/listening-to-music.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 | $0.00251 | $0.02670 |
| Opus 5.5 | $0.00100 | $0.01068 |
| Sonnet 5.5 | $0.00050 | $0.00534 |
| Haiku 4.5 | $0.00025 | $0.00267 |
Grade A, and why
listening-to-music 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 21d 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 — 149 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Listening to music
Claude hears nothing, but it can render audio in the real engine and measure it. Set up the loop render → look → measure → change one thing → re-render, and keep a table of the numbers per version. A version is better when a number you chose beforehand moves by more than the take-to-take noise, and the spectrogram shows the same thing.
Requirements: Node with playwright and Chromium (preinstalled in Claude Code on the web),
Python with librosa soundfile scipy matplotlib pillow, and for sheet music
music21 verovio mir_eval cairosvg
(pip install --break-system-packages librosa music21 verovio mir_eval cairosvg). The first render installs @strudel/web into
~/.cache/listening-to-music/. All scripts live in scripts/; run them with --help or read the
docstring for options.
1. Render
S=/path/to/listening-to-music/scripts
node $S/render_strudel.mjs loop.js --out v1.wav --seconds 40 --warmup 4 # Strudel code
node $S/record_page.mjs page.html --click "#power" --out v1.wav --seconds 40 --warmup 8 \
--query "station=house" --eval "window.__fm.setSeed(7)" # any Web Audio page
Both print peak level and flag clipping. A peak above 1.0 means the listener hears hard clipping; fix levels before judging anything else.
For a before/after comparison, fix the randomness (a seed hook via --eval) so both versions
play the same material, and record each version twice.
2. Look
python3 $S/spectrogram.py v1.wav --out v1.png --from-onset --pyin-floor G3 --label v1
Then open v1.png with the image viewer. The top panel is a note-axis CQT spectrogram with the
pYIN lead line, and the bottom panel is chroma. Compare it with the reference picture or the
previous version side by side. The .npz next to it holds the numbers for step 3.
3. Measure
| Question | Tool | Reads |
|---|---|---|
| Do simultaneous notes rub? (discordant chords) | render_strudel.mjs --events → clashes.py |
minor 2nd/9th overlap per cycle, by layer pair; worst moments |
| Do they rub in the recording? | rubs.py, --pair for replicated takes |
share of tonal peak energy in semitone/minor-9th pairs |
| Is it rougher or smoother overall? | roughness.py, --pair for replicated takes |
Sethares roughness median/p90 |
| Does it match a reference image? | reference.py ticks/decode/compare |
per-semitone profile, melody agreement, overtone offsets, chroma agreement |
| Is the melody audible over the mix? | spectrogram.py pYIN voiced %, reference.py compare melody % |
What ships with it
16 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- CHANGELOG.md 2.1 KB
- scripts/clashes.py 3.3 KB runs code
- scripts/common.mjs 3.9 KB runs code
- scripts/compare_notes.py 4.3 KB runs code
- scripts/notes.py 4.2 KB runs code
- scripts/read_score.py 4.8 KB runs code
- scripts/record_page.mjs 2.0 KB runs code
- scripts/reference.py 8.8 KB runs code
- scripts/render_strudel.mjs 4.3 KB runs code
- scripts/roughness.py 3.8 KB runs code
- scripts/rubs.py 3.0 KB runs code
- scripts/score.py 4.0 KB runs code
- scripts/spectrogram.py 3.3 KB runs code
- scripts/tap.js 2.5 KB runs code
- scripts/to_strudel.py 3.0 KB runs code
- scripts/transcribe.py 5.8 KB runs code
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.
- 21d ago First seen · 149 lines · 251 tokens per session scan A 9958c55fc3f1
listening-to-music is a skill published in the GitHub repository oaustegard/claude-skills (153 stars, last pushed yesterday), licensed MIT. It adds 251 tokens to every session and 2,670 once invoked, about $0.0010 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 2026-09-26.
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