Chord

Chord — connector documentation

• MCP endpoint: https://chord.connectorbay.com/mcp
• REST API: POST https://chord.connectorbay.com/v1/tools/{tool_name}, described by the OpenAPI 3.1 spec at https://chord.connectorbay.com/openapi.json
• Transport: Streamable HTTP, stateless, MCP specification 2025-06-18 or later
• Authentication: none required. An optional Authorization: Bearer <key> raises rate limits.
• Health: https://chord.connectorbay.com/health · Tool schemas: https://chord.connectorbay.com/tools.json
• Publisher: Unify Dynamics LLC · connectorbay.com/chord · agent@connectorbay.com

What Chord is for

The music-theory questions a player, songwriter or student asks mid-session: what notes are actually in an Fm7b5, what chord is this weird set of notes I just played, what scale goes over this key, what's the key signature and diatonic chords of E minor, what should I call this progression, how do I transpose this for a singer with a different range, what's the interval between two notes, what a chord actually looks like on a guitar neck in an alternate tuning, what note a frequency is (for tuning by ear or by app), and what's on the circle of fifths.

What it does

Chords — parse a chord symbol (triads, sixths, sevenths, ninths, elevenths, thirteenths, sus, add9, altered dominants, slash chords) into its notes, intervals and formula; or go the other way and identify a chord from a set of notes. Scales — the notes of major, natural/harmonic/melodic minor, all seven modes, major/minor pentatonic, blues, whole tone and chromatic in any key. Keys — key signature (sharps or flats), relative and parallel key, and the full set of diatonic triads/sevenths with roman numerals. Progressions — turn roman numerals into real chords in a key, and recognize well-known progressions (I-V-vi-IV, ii-V-I, 12-bar blues, rhythm changes, the Andalusian cadence and more). Transpose — shift a list of chords or notes by semitones or between two keys. Intervals — the named interval and consonance between any two notes. Guitar shapes — a genuine fretboard search engine (not a fixed lookup table) that brute-forces every fret combination on standard or alternate tunings (drop D, open G/D, DADGAD, half-step down, ukulele, bass) and ranks the results by playability, so it can find a shape for literally any chord you throw at it, not just the common ones. Frequencies — note-to-Hz and Hz-to-nearest-note with cents-off, for tuning. Circle of fifths — the full circle with relative minors and key signatures.

What it is not

A theory engine, not a source of copyrighted sheet music, tabs or song data — nothing here reproduces an actual song. The guitar-shape search favors playability (fewer muted strings, smaller stretch, open strings, root in the bass) but doesn't know your hand size or style; treat it as a strong starting set, not the only correct fingering.

Tools

Chords & scales

chord_notes — Notes, intervals and formula of a chord symbol, with slash-chord bass support. Use for "what notes are in Cmaj7", "what's a G7#9". Args: chord.

chord_identify — Identify which chord(s) a set of notes could be. Use for "what chord is A C# E G". Args: notes, bass.

scale_notes — Notes of a scale or mode in any key. Use for "notes of D dorian", "A minor pentatonic scale". Args: root, scale.

Keys & progressions

key_info — Key signature (sharps/flats), relative and parallel key, and the full diatonic chord set with roman numerals. Use for "key signature of E minor", "diatonic chords in G major". Args: key.

progression_build — Turn roman numerals into real chords in a key, and name the progression if it's a well-known one (I-V-vi-IV, ii-V-I, 12-bar blues, etc). Use for "turn I-V-vi-IV into chords in G". Args: key, roman_numerals.

transpose — Transpose a list of chords or notes by semitones, or from one key to another. Use for "transpose this progression up a whole step", "transpose from G to Bb". Args: items, semitones, from_key, to_key.

Ear & fretboard

interval_between — The named interval and consonance between two notes. Use for "interval between C and G". Args: note1, note2.

guitar_chord_shapes — Genuinely computed playable fretboard shapes for any chord (a real fretboard search, not a fixed lookup table), ranked by playability, in standard or alternate tunings. Use for "guitar shapes for Bm7". Args: chord, tuning, max_fret, limit.

note_frequency — Convert a note+octave to its frequency in Hz, or a frequency to the nearest note and cents off (a tuner). Give exactly one of note or frequency_hz. Use for "frequency of A4", "what note is 220 Hz". Args: note, frequency_hz, a4_hz.

Reference

circle_of_fifths — The circle of fifths: all 12 major keys with relative minors and key signatures. Use for "circle of fifths", "what's next to D on the circle of fifths". Args: highlight.

Conventions

• Read-only. Every tool reads public data or computes; nothing is written anywhere and nothing about the user is stored.
• Result envelope. ok: true with data, or ok: false with a structured error (bad_input, not_found, upstream_error). degraded lists optional sources that were unreachable.
• Rate limits. Free tier 60 tool calls/minute and 300/day per user (keyed on the user identifier supplied by the host agent, else client IP); Pro keys raise this. Over-limit calls return HTTP 429 with Retry-After. initialize and tools/list are never counted.

Support

agent@connectorbay.com · connectorbay.com/chord/support

Chord — Privacy Policy

Effective 23 September 2026. Unify Dynamics LLC ("we", "us"), Menlo Park, California.

What Chord is. Chord is a connector (an MCP server and REST API) that AI assistants and personal agents call on your behalf for music theory: chord and scale lookups, key and progression analysis, transposition, intervals, guitar fretboard shapes, note/frequency conversion and the circle of fifths. You interact with your assistant; the assistant sends us only the chord symbol, notes, key, or numbers needed for that one calculation.

What we receive. The arguments of each tool call — a chord symbol or list of notes, a scale/key name, roman numerals, a semitone shift or pair of keys, two notes for an interval, a chord and tuning for a fretboard search, a note or frequency — the technical headers needed to serve the request (an IP address or a client identifier supplied by the assistant, and a Pro API key if you have one), and standard server logs.

Everything is computed on our server and nothing is stored. Every tool is a music-theory calculation from first principles (pitch-class arithmetic, a brute-force fretboard search); no request is forwarded to any third party, no song data or copyrighted sheet music is used or returned, and no input is logged in request bodies, recorded, or used to train anything.

What we do not receive or store. We do not receive your conversation with the assistant, your name, contacts, or account credentials. Rate-limit counters (a client identifier and timestamps) are held in memory for at most 24 hours. Hosting-provider access logs, which contain IP addresses and request paths but not request bodies, are retained for up to 30 days for security and abuse prevention.

Sub-processors. None — every tool is computed locally. Hosting: Vercel (United States regions).

Legal bases and your rights. For users in California, the EU/UK and elsewhere, our processing is necessary to provide the service you request through your assistant. Because we store no personal data beyond short-lived logs, requests to access, correct or delete personal data are usually satisfied automatically; you can still contact agent@connectorbay.com and we will respond within 30 days. We do not sell or share personal information and do not use your data to train models.

Children. Chord is a general-audience service operated by the adult using the assistant.

Changes. We will post changes here with a new effective date.

Chord — Terms of Service

Effective 23 September 2026. These terms govern use of the Chord connector ("the Service") operated by Unify Dynamics LLC ("we", "us").

1. The Service. Chord returns music-theory results — chord and scale analysis, key and progression information, transposition, intervals, computed guitar fretboard shapes, note/frequency conversion, and the circle of fifths — computed locally from standard music theory. It is accessed through an AI assistant or directly over MCP or HTTP.
2. Original computation, not song data. Every result is derived mathematically from pitch-class arithmetic and a fretboard search; the Service does not store, look up, or return copyrighted sheet music, tablature, or song arrangements of any kind.
3. Not a substitute for a teacher. Guitar-shape rankings favor general playability, not your hand or style; use your own judgment or a qualified instructor for technique.
4. Acceptable use. Do not use the Service to mass-generate content for redistribution as if it were sourced sheet music or tab archives. Automated use within the published limits is welcome.
5. Availability. The Service is provided "as is" without warranty. We may change, limit or discontinue it at any time.
6. Data. Our Privacy Policy describes what we process. In short: your query is answered on our server and nothing is stored.
7. Pro keys. Optional Pro API keys are issued at our discretion, are personal to the holder and may be revoked for abuse.
8. Liability. To the fullest extent permitted by law, Unify Dynamics LLC is not liable for any loss arising from use of or reliance on the Service. Our total liability is limited to US $100.
9. Governing law. California law; venue in San Mateo County, California.
10. Contact. Unify Dynamics LLC · agent@connectorbay.com · https://connectorbay.com/chord

Chord support

Email agent@connectorbay.com. We answer within two business days.

• MCP endpoint: https://chord.connectorbay.com/mcp
• REST API: https://chord.connectorbay.com/openapi.json
• Live status: https://chord.connectorbay.com/health

When you report a problem, include the question you asked your agent, roughly when, and which agent you used (for example Claude, ChatGPT or Gemini). Never send us passwords, account numbers or ID numbers. Chord never asks for them.