{"uid":"cap_XpSMBxbhBR5tH3IDh9blk","slug":"music-theory-roman-numeral-analysis-2b20166b","name":"Music Theory Roman Numeral Analysis","description":"Roman numeral analysis of a chord progression in a key: numerals, inversions, borrowed chords, secondary dominants.","url":"https://music-theory.x402tookit.com/roman-numerals?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":["key","progression"],"properties":{"key":{"type":"string","description":"Key of the progression: C, G, Am, F# minor"},"progression":{"type":"string","description":"Chords separated by spaces, commas or bars: C Am F G7"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"key":{"type":["null","string"]},"asOf":{"type":["null","string"]},"source":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"summary":{"type":["null","string"]},"verdict":{"type":["null","string"]},"analysis":{"type":["array","null"],"items":{"type":"object","properties":{"role":{"type":["null","string"]},"root":{"type":["null","string"]},"chord":{"type":["null","string"]},"numeral":{"type":["null","string"]},"diatonic":{"type":["boolean","null"]},"diatonicNote":{"type":["null","string"]},"degreeFromTonic":{"type":["null","number"]}}}},"degraded":{"type":["boolean","null"]},"numerals":{"type":["array","null"],"items":{"type":"string"}},"disclaimer":{"type":["null","string"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}}}}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.02","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.02/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_Om6oc36CDCCIgqTBJYjD5","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.02","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Analyzes a chord progression in a given key and returns Roman numeral notation including inversions, borrowed chords, and secondary dominants.","exampleAgentPrompt":"Can you do a Roman numeral analysis of the progression C Am F G7 in the key of C major — I want to know if any chords are borrowed or act as secondary dominants?","exampleUseCases":[{"title":"Songwriting harmonic analysis","prompt":"I wrote a progression in G major: G Em C D7 Am D7 G — can you label each chord with Roman numerals and tell me which ones are diatonic, borrowed, or secondary dominants?"},{"title":"Music theory homework check","prompt":"My homework asks me to analyze the progression Dm G7 C Fmaj7 Am7 E7 in C major using Roman numerals with inversions — can you work that out for me?"},{"title":"Identifying borrowed chords in a song","prompt":"The song I'm transcribing is in A minor and uses Am F C G E7 — can you give me the Roman numeral analysis and flag any borrowed or non-diatonic chords?"}],"resultDescription":"Returns a list of Roman numeral labels for each chord in the progression, including inversion notation, diatonic status, degree from tonic, borrowed chord flags, and secondary dominant roles, plus a summary and any unrecognized chords.","failureModes":["Unrecognized chord symbol returns it in 'notChecked' array with partial results","Invalid or ambiguous key string may return null key or degraded analysis","Chords with complex extensions may not be fully analyzed","Missing required 'key' or 'progression' query parameter returns an error"],"whenToPreferThis":"Use this endpoint when you need structured Roman numeral harmonic analysis of a chord progression in a specific key, including identification of inversions, borrowed chords, and secondary dominants. Prefer this over manual analysis or general music info APIs when you need machine-readable harmonic function labels for each chord.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-29T13:12:39.055Z","isFirstParty":false,"canonicalSlug":"music-theory-roman-numeral-analysis-2b20166b"}