# Music Production Calc: Key Shift

> Music Production Calc: Key Shift is a paid API for AI agents from music-production-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-11-03).

Shifts a musical key by a given number of semitones, returning the correctly spelled destination key, its mode, relative key, key signature, and capo chord shapes.

## Facts

- Endpoint: GET https://music-production-calc.x402tookit.com/key-shift?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-03
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/music-production-calc-key-shift-e269a6eb
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_BnCXY2k4W42Ot19SSrBlt

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability music-production-calc-key-shift-e269a6eb
```

Example prompt: I'm playing a song in F# major and need to transpose it up 3 semitones — can you tell me the resulting key with the correct sharp or flat spelling, its key signature, relative minor, and capo shapes if I'm using a capo?

## When to prefer this

Use this endpoint when you need musically correct transposition with proper enharmonic spelling (e.g. F# vs Gb), key signature, relative key, and guitar capo chord shapes — rather than a simple chromatic lookup table or a generic music theory library that may not handle enharmonic spelling or capo logic.

## Known failure modes

- Invalid key string format returns an error (e.g. unrecognized key name)
- Semitones outside -24 to 24 range rejected
- Capo fret outside 1–11 range rejected
- Missing required query parameters (key or semitones) returns 400-level error

## How this service works

Shift a key by semitones with the right sharp or flat spelling, its relative major or minor, signature and capo shapes.

## Output

Returns the destination key name with correct sharp or flat spelling, mode (major/minor), relative key, key signature (e.g. '3 sharps'), number of semitones shifted, fifths position, and an array of capo options each with fret number, chord-shape key, key signature, and open-friendly flag.

## Request schema (JSON Schema)

```json
{
 "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",
      "semitones"
     ],
     "properties": {
      "key": {
       "type": "string",
       "description": "Starting key: C, F#, Bb, Am, F#m or 'Bb minor' (no mode means major)"
      },
      "capo": {
       "type": "integer",
       "description": "Capo fret 1 to 11 to get the chord-shape key to play (optional)"
      },
      "prefer": {
       "type": "string",
       "description": "sharps or flats, used only when two spellings are equally simple (for example F# or Gb major)"
      },
      "semitones": {
       "type": "integer",
       "description": "Shift in semitones, -24 to 24 (positive is up)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "toKey": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "toMode": {
       "type": [
        "null",
        "string"
       ]
      },
      "fromKey": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "capoChoice": {},
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "notChecked": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "capoOptions": {
       "type": [
        "array",
        "null"
       ],
       "it
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/music-production-calc-key-shift-e269a6eb/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from music-production-calc.x402tookit.com](https://www.zero.xyz/host/music-production-calc.x402tookit.com/llms.txt)