Music Production Calc
The 7 triads and 7th chords of a key (major, natural or harmonic minor) with spelled notes and Roman numerals.
OtherLiveeip155:8453Exactvia cdp
ChordsKeyHarmonyRoman-numeralsSongwriting
Calls · 30d
1
This endpoint's own trailing-30-day call count, as published by the upstream catalog and snapshotted daily. 4 snapshots so far.
$24.31
Verified settled volume
1,175 settlements proven x402 by their on-chain EIP-3009 marker.
$0.020
Listed price
As published in the catalog. Always read the live 402 before paying.
1
Calls · 30d
Upstream's own call count for this endpoint, not ours.
1
Unique payers · 30d
Last called 2026-10-20 20:34Z
—
Upstream on-chain volume
Reported by the source catalog.
Paid to
0xb531320805C5BED1D46AEaDcF4F008FDF172DBDaThe wallet the 402 directs payment to. Its whole payment record — every payer, every chain — is on the merchant page.
Asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
Provider
The payTo wallet does not resolve to a registered ERC-8004 agent. That is not a verdict on the service — most of the catalog is unregistered.
Live 402 challenge
Captured by the enrichment pass, not read just now. Prices can change — always read the 402 the endpoint answers with.
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"F",
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],
"seventhNotes": [
"D",
"F",
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],
"triadQuality": "minor"
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"source": "computed locally (stacked thirds on each scale degree; each note keeps its own letter name)",
"reasons": [
"Each chord stacks the scale degrees a third apart (1-3-5, then 7), so the spelling follows the scale and never uses an enharmonic respelling.",
"Lower-case numerals are minor or diminished, upper-case are major."
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"Lower-case numerals are minor or diminished, upper-case are major."
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"scaleUsed": "major",
"signature": "no sharps or flats",
"disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
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],
"triadQuality": "minor"
}
],
"source": "computed locally (stacked thirds on each scale degree; each note keeps its own letter name)",
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"Each chord stacks the scale degrees a third apart (1-3-5, then 7), so the spelling follows the scale and never uses an enharmonic respelling.",
"Lower-case numerals are minor or diminished, upper-case are major."
],
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"verdict": "COMPUTED",
"degraded": false,
"scaleUsed": "major",
"signature": "no sharps or flats",
"disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
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"chords borrowed from other keys or modes, and secondary dominants",
"modes beyond major, natural minor and harmonic minor (melodic minor and church modes)",
"…1 more"
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"D",
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"catalog": "https://music-production-calc.x402tookit.com/catalog",
"message": "Music Production Calc has 9 pay-per-call endpoints (Studio arithmetic: tempo grids, song length, tap tempo, key shifts and capo, Camelot mixing, diatonic chords, fretboard notes, pitch-speed and delay tails.), from $0.02 a call. See the full menu and send your agents our way.",
"openapi": "https://music-production-calc.x402tookit.com/openapi.json",
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"url": "https://music-production-calc.x402tookit.com/key-shift",
"path": "/key-shift",
"what": "Shift a key by semitones with the right sharp or flat spelling, its relative major or min…",
"price": "$0.02"
},
{
"url": "https://music-production-calc.x402tookit.com/camelot-key",
"path": "/camelot-key",
"what": "Camelot wheel code for a musical key and its harmonic-mixing matches; optionally test if…",
"price": "$0.02"
},
{
"url": "https://music-production-calc.x402tookit.com/fret-note",
"path": "/fret-note",
"what": "Note name, MIDI number and Hz at a fret on guitar, bass, ukulele or violin strings, with…",
"price": "$0.02"
}
]
}
}Accepts
The payment requirements as published to the catalog. Read the live 402 before paying — a price here is a claim, not a quote.
0.02USDC≈ $0.02 USD
on Base · exact scheme
Pay 0.02 USDC on Base to 0xb531…2DBDa. The signed payment is good for 5 minutes.
- Paid to
- 0xb531…2DBDa
- USD Coin contract
- 0x8335…02913
- Payment window
- 5 minutes
- As published
- 20000 smallest units
20000units
on solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp · exact scheme
That figure is in the token’s smallest units. Roundhouse does not hold this contract’s decimals, so it is shown as published rather than converted.
- Paid to
- DUPiup…eEm8s
- Token contract
- EPjFWd…TDt1v
- Payment window
- 5 minutes
20000units
on Polygon · exact scheme
That figure is in the token’s smallest units. Roundhouse does not hold this contract’s decimals, so it is shown as published rather than converted.
- Paid to
- 0xb531…2DBDa
- Token contract
- 0x3c49…c3359
- Payment window
- 5 minutes
20000units
on Arbitrum · exact scheme
That figure is in the token’s smallest units. Roundhouse does not hold this contract’s decimals, so it is shown as published rather than converted.
- Paid to
- 0xb531…2DBDa
- Token contract
- 0xaf88…e5831
- Payment window
- 5 minutes
The catalog’s raw entry
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{
"bazaar": {
"info": {
"input": {
"type": "http",
"method": "GET",
"queryParams": {
"key": "C"
}
},
"output": {
"type": "json",
"example": {
"key": "C major",
"asOf": "2026-10-12T01:46:28.079Z",
"chords": [
{
"roman": "I",
"triad": "C",
"degree": 1,
"seventh": "Cmaj7",
"triadNotes": [
"C",
"E",
"…1 more"
],
"seventhNotes": [
"C",
"E",
"…2 more"
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"triadQuality": "major"
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{
"roman": "ii",
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"F",
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"source": "computed locally (stacked thirds on each scale degree; each note keeps its own letter name)",
"reasons": [
"Each chord stacks the scale degrees a third apart (1-3-5, then 7), so the spelling follows the scale and never uses an enharmonic respelling.",
"Lower-case numerals are minor or diminished, upper-case are major."
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"verdict": "COMPUTED",
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"scaleUsed": "major",
"signature": "no sharps or flats",
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"properties": {
"key": {
"type": "string",
"description": "Key: C, F#, Bb, Am, F#m or 'Bb minor' (no mode means major)"
},
"scale": {
"type": "string",
"description": "major, minor (natural) or harmonic-minor; default follows the key's mode"
}
}
}
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}Provenance
- Seen in the source catalog
- 2026-10-20 20:34Z
- Last indexed by Roundhouse
- 2026-10-22 06:50Z
- Last enriched (probe, favicon, geo)
- 2026-10-20 23:15Z
- x402 version
- 2
- Max timeout
- 300s
- Liveness probe
- HTTP 402
Hand this page to an agent
Copy the prompt and paste it into Claude, an MCP client or your own agent — it will vet this service and call it over the free read API. No key, no account.
GET api.roundhouseai.io/v0/endpoints
This endpoint's own trailing-30-day call count, as published by the upstream catalog and snapshotted daily. 4 snapshots so far. Verified volume counts only settlements with an on-chain EIP-3009 marker.
Show the promptHide the prompt
Using Roundhouse, look up the x402 service Music Production Calc and tell me whether it is worth paying: what a call costs, whether the endpoint answered when last probed, and what its payment record actually shows. curl -s 'https://api.roundhouseai.io/v0/endpoints?q=Music%20Production%20Calc' curl -s 'https://api.roundhouseai.io/v0/merchants/<the payTo wallet returned above>' Then call it: read the price from the live 402 at https://music-production-calc.x402tookit.com/diatonic-chords, never from a cached figure, and pay with an x402 client. The /v0 API needs an API key (`authorization: Bearer rh_live_…`) on everything except /v0/unified* and /v0/endpoints. Either pay over x402 (mint a personal key for $0.01 at GET https://api.roundhouseai.io/v0/test/x402), or ask me for an organization key, which I create at https://roundhouseai.io/dashboard/connections. If you have neither, ask before going further. If you do not have Roundhouse tools or skills installed, read https://roundhouseai.io/skill.md first — it is the whole procedure.