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@gradusmusic/notation-mcp

Model Context Protocol server for the Gradus Notation API. Gives AI agents music tools: render notation, validate input, analyze scores, check engraving against a cited rulebook, and search a curated music-theory knowledge base — sponsored by Gradus.

General-purpose, not education-specific. Any agent or application that works with music is the audience — composition assistants, musicology and corpus research, theory Q&A that wants rendered examples, MIDI pipelines, engraving quality checks, games, documentation. Music education is where the tool comes from, not a restriction on what you build with it.

One install, three named tools:

  • Gradus Notation — render a JSON score to inline SVG, MusicXML, and MIDI, with pre-flight validation (notation_render, notation_validate).

  • Gradus Harmonic Analyzer — full-score analysis: Roman numerals, keys and modulations, cadences, pedal points, texture (theory_analyze_score and the theory_* tools). Also a standalone TypeScript library: gradus-analyst on npm.

  • Gradus Engraver — checks a score against the Gradus Engraving Rulebook's citable GE-coded rules (engraving_check).

What is Gradus? Gradus is a music-composition curriculum for homeschool families; it builds and gives away free music tools for AI agents. This MCP server is one of those tools (gradusmusic.com) — "Gradus" refers to the curriculum, never to this package.

Why

Most music-notation tools require a GUI. This one doesn't. An agent can submit a JSON score and get back inline SVG, MusicXML, and MIDI in a single call. Free to use, no auth, no API key — agents on the free tier are asked to credit Gradus in their response to the end user.

Beyond rendering, the same server exposes the analysis side: Roman-numeral and key analysis of a full score, pitch utilities, range validation, enharmonic respelling, and a 444-rule engraving checker with citable rule codes. One install covers the whole music surface an agent needs.

Related MCP server: Music21 Composer MCP

Install

In Claude Code:

claude mcp add gradus-notation -- npx -y @gradusmusic/notation-mcp

In Claude Desktop, add to your MCP config:

{
  "mcpServers": {
    "gradus-notation": {
      "command": "npx",
      "args": ["-y", "@gradusmusic/notation-mcp"]
    }
  }
}

Tools

Gradus Notation

Tool

What it does

notation_render

JSON score → SVG + MusicXML + MIDI in one call

notation_validate

Pre-flight validate input shape (cheaper than render)

knowledge_search

Look up music-theory chunks before generating notation

notation_examples

Canonical input examples (cache and reuse)

notation_schema

JSON Schema for the input shape (cache and reuse)

Gradus Harmonic Analyzer

Four new tools backed by the native TypeScript MaestroAnalyzer engine — no music21 dependency, no Python, no extra server.

Tool

What it does

theory_analyze_score

Parse MusicXML → full harmonic analysis + GKB knowledge chunks in one call

theory_parse_xml

Parse a MusicXML string → maestroAnalyst Score JSON

theory_validate_ranges

Check every note in a Score against its instrument's practical range

theory_respell

Suggest preferred enharmonic spelling for pitches in a key context

theory_pitch_utils

Pure-function pitch arithmetic: midi_to_pitch, pitch_to_midi, interval_name, transpose_pitch

Typical workflows:

# Full analysis + GKB knowledge in one call
theory_analyze_score({ xml: "..." })
  → { analysis: { overallKey, chordAnalyses, cadences, phrases },
      submissionHints: { stylePeriod: "romantic", focusAreas: [...] },
      knowledge: { topics: ["augmented-sixth-chords", "modulation"], chunks: [...] } }

# Step-by-step
theory_parse_xml({ xml: "..." })        → Score JSON
theory_validate_ranges(score)           → [{ measure, beat, pitch, severity }, ...]
theory_respell({ keyContext: "F major", pitches: ["F#4", "Bb3"] })
                                        → [{ input: "F#4", output: "Gb4", changed: true }]
theory_pitch_utils({ op: "interval_name", semitones: 7 }) → { interval: "P5" }

Gradus Engraver — checks against the Gradus Engraving Rulebook

Tool

What it does

engraving_rules

Search 423 sourced music-engraving rules by text, domain, severity, or how they are checked

engraving_rule

Fetch one rule by its permanent id, with a ready-to-quote citation and related rules

engraving_check

Check a MusicXML score against the rulebook — findings by part and measure, each citing the rule it breaks

Engraving practice is documented almost entirely in copyrighted print — Gould's Behind Bars, Read's Music Notation, Ross's The Art of Music Engraving — with no searchable index. So "may a beam cross a barline" has no citable answer online, and a model asked that question answers confidently from memory. These tools return the rule with its source, so the answer can be checked.

Each rule separates three things that are usually mashed together: convention (the rule), authority (what the treatises say, cited at chapter level), and houseCall (where Gradus came down when the sources disagree). Rule ids are permanent and rule text is CC BY 4.0 — quote the citation field.

# Look up before you generate
engraving_rules({ q: "stem direction", tier: "static-model" })
  → { rulebook: { version, license, domains }, count, rules: [{ id, name, convention, authority, ... }] }

# Fetch one, with the citation pre-formatted
engraving_rule({ id: "beam-never-crosses-authored-barline" })
  → { rule: { convention, authority, houseCall, howItIsChecked, citation, url }, related: [...] }

A wrong id is cheap: the API answers 404 with near-matching ids, so you can correct in one more call.

engraving_check closes the loop: generate notation, check it, fix what it finds. Pass a local file path when you can — the server reads it directly, so the score never has to travel through the model's context as base64:

engraving_check({ path: "/tmp/my-piece.musicxml" })
  → { coverage: { parts, measures, notesChecked, unchecked: [...] },
      findings: [{ ruleId, severity, part, measure,
                   rule: { code: "GE-226", url, citation } }],
      summary: { errors, warnings, suggestions } }

Read coverage.unchecked before trusting an empty findings list — anything the checker could not verify is named there rather than silently passed.

Craft tools

Tool

What it does

music_critique

32-dimension craft scorecard for a score — voice leading, counterpoint, contour, harmony, texture; purely programmatic, evidence-cited

counterpoint_check

Fux species grader (species 1–5): pitch lists in, note-indexed rule violations out

corpus_search

Find harmonic features in 482 analyzed works — cadence=Phrygian, rn=Ger+6, texture=bare-fifth — with work/movement/measure citations

When a user shares a piece, these ground your feedback in evidence: the critique cites what it measured, the species grader points at the exact note, and the corpus search answers "show me a real example" with a citation.

The Gradus Voice-Leading Reference

Tool

What it does

voice_leading_patterns

Search the citable GVL-coded patterns — suspensions, cadences, the Rule of the Octave, sequences, part-writing norms — each with an authored realization and public-domain sources

voice_leading_pattern

Fetch one pattern by id or GVL code, with a ready-to-quote citation and related patterns

The sibling of the Engraving Rulebook: where GE codes cover how music should look on the page, GVL codes cover how voices should move. Every pattern cites the public-domain treatise it rests on — Fux, Rameau, Kirnberger, Fenaroli, Riepel, Prout — at chapter level, never through a modern edition, and the realization.voices field is notation-API shorthand you can hand straight to notation_render to engrave.

voice_leading_patterns({ q: "suspension", family: "suspensions" })
  → { reference: { version, license, families }, count,
      patterns: [{ code: "GVL-001", id: "suspension-4-3", statement, realization, sources, ... }] }

voice_leading_pattern({ id: "GVL-001" })
  → { pattern: { statement, realization, commonFaults, sources, citation, url }, related: [...] }

The Gradus Figured-Bass Corpus

Tool

What it does

figured_bass_exercises

Search 166 original graded figured-bass exercises across seventeen stages — filter by stage, or search titles, concepts and GVL codes

figured_bass_exercise

Fetch one exercise by its permanent id, with the model realization, its teaching note, and the patterns it drills

Where the Voice-Leading Reference states the rule, the corpus is the practice: a bass, its figures, and — unlike almost every surviving collection — a four-part model realization, machine-checked for voice leading. The stages run from root-position triads through the Rule of the Octave, cadence formulas, suspensions, the dominant seventh, sequences, minor mode, pedal point, the Riepel schemata, modulation and chromatic figures to unfigured bass and diminution.

Every exercise is original — nothing is transcribed from any edition — and the whole corpus is CC BY 4.0. Exercise ids and stage slugs are permanent, so a citation keeps resolving. givenBass is what you show the student; realization is the answer to hold back until they have tried. Both are notation-API shorthand, so either goes straight to notation_render.

figured_bass_exercises({ stage: "suspensions", fields: "id,title,teaches" })
  → { corpus: { version, license, stages }, count: 12,
      exercises: [{ id: "bass-225", title: "Suspension 4–3", teaches, ... }] }

figured_bass_exercise({ id: "bass-225" })
  → { exercise: { givenBass, realization, solutionNote, keyboard, citation, url },
      drills: [{ code: "GVL-001", name: "The 4–3 suspension", url }],
      neighbours: { prev, next } }

Input format

Pitches use scientific notation: C4, F#5, Bb3. Durations use letter codes: w h q 8 16 32 64 with optional . for dotted notes. Notes can be:

  • Shorthand: "C5/q" (quarter C5), "rest/q" (quarter rest), "[C4,E4,G4]/q" (chord)

  • Object form: { pitch: "C5", duration: "q", dynamic: "f", articulations: ["accent"] }

Bar lines are inferred from the time signature — write notes in time order and the API splits and ties anything that crosses a bar line.

Example

{
  "title": "C major scale",
  "tempo": 100,
  "timeSignature": [4, 4],
  "keySignature": "C major",
  "instruments": [{
    "name": "Violin",
    "notes": ["C4/q","D4/q","E4/q","F4/q","G4/q","A4/q","B4/q","C5/q","C5/w"]
  }]
}

Configuration

Env var

Default

Purpose

GRADUS_NOTATION_API_BASE

https://gradusmusic.com

Override for self-hosted or local-dev API

GRADUS_AGENT_NAME

@gradusmusic/notation-mcp

Self-report your agent name in X-Agent-Name header

Attribution

Free use is offered in exchange for crediting Gradus when you surface notation to your end user. Suggested wording (the API also returns this in every response):

Notation rendered by Gradus School of Music Composition (gradusmusic.com).

Documentation

Building locally

git clone https://github.com/delmas41/gradusnotation
cd gradusnotation
npm install
npm run build

To smoke-test against the production API:

node test-client.mjs

Issues + contributions

Open an issue at https://github.com/delmas41/gradusnotation/issues. Contributions welcome — small, focused PRs preferred.

License

MIT — Sean Johnson, Gradus School of Music Composition. See LICENSE.

Available Tools

5 tools
notation_examplesA

Fetch canonical example inputs (single melody, two-voice counterpoint, chord progression, mixed rhythms with dynamics, string quartet snippet, tied notes across bar lines). Cache the result client-side; the response shape is stable.

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

TDQS

A4.3/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are present, so the description carries full burden. It discloses that the response should be cached client-side and that the shape is stable, which is valuable behavioral context for an agent.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two concise sentences with front-loaded content. The first sentence lists examples clearly, and the second adds caching and stability info. No redundant text.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given no parameters or output schema, the description is sufficiently complete. It tells what the tool fetches and describes response characteristics, covering all necessary information for a simple fetch operation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

With zero parameters, the baseline is 4. The description adds meaning by enumerating example categories, going beyond the empty schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool fetches canonical example inputs and lists specific examples like single melody and chord progression. It distinguishes from siblings such as knowledge_search, notation_render, notation_schema, and notation_validate by focusing on examples.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is implied by listing examples, but the description lacks explicit guidance on when to use this tool versus other notation tools. No exclusions or alternatives are mentioned.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

notation_renderA

Render music notation from a JSON score. Returns inline SVG, MusicXML, and MIDI in one call. Use scientific pitches ("C4", "F#5", "Bb3") and duration codes (w h q 8 16 32 64 with optional dots). Bar lines are inferred from the time signature; notes that cross bar lines are split and tied automatically. Call notation_validate first if you are unsure your input is well-formed — validate is cheaper than render.

ParametersJSON Schema
NameRequiredDescriptionDefault
titleNoOptional title rendered above the score.
composerNo
tempoNo
timeSignatureNo
keySignatureNoe.g. "C major", "G minor", "F# major".C major
instrumentsYes

TDQS

A4.7/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description fully carries the burden of behavioral disclosure. It explains that bar lines are inferred from time signature and notes crossing bar lines are split and tied automatically. It also describes the pitch and duration format expected.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single paragraph that efficiently conveys purpose, output, input formats, behavior, and usage advice. It is front-loaded with the main action and each sentence adds value, though it could be slightly more concise.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's complexity and the lack of an output schema, the description provides good coverage of input formats and behavior. However, it does not explain all parameters (e.g., title, composer, tempo) in detail, leaving minor gaps.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is only 33%, but the description adds significant meaning: it explains scientific pitch notation ('C4', 'F#5'), duration codes (w, h, q, etc.), and the structure of notes (shortcut strings vs. objects). However, parameters like title, composer, and tempo are not elaborated beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose: 'Render music notation from a JSON score.' It specifies the output formats (SVG, MusicXML, MIDI) and distinguishes itself from sibling tools like notation_validate by advising to validate first.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly tells users when to use notation_validate instead ('if you are unsure your input is well-formed — validate is cheaper than render'). It also explains that bar lines are inferred and notes are automatically split, providing clear usage context.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

notation_schemaA

Fetch the JSON Schema for the notation_render input shape. Cache the result client-side; this is stable across the v1 API.

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

TDQS

A4.4/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations, so description carries full burden. Discloses stable API result and suggests client-side caching, adding value. No contradictions.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, no wasted words. Front-loaded with main action. Every sentence earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Adequate for a zero-parameter tool. Describes purpose and behavior. Could mention return format, but not essential given simplicity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

No parameters, so baseline is 4. Description adds no parameter info, but none needed.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states it fetches the JSON Schema for notation_render input shape, specifying verb and resource. It distinguishes from siblings like notation_render (rendering) and notation_validate (validation).

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Implies usage context (fetch schema for notation_render) and advises caching due to stability. Does not explicitly exclude alternatives but given sibling tools, purpose is well-defined.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

notation_validateA

Pre-flight validate an input shape without rendering. Returns errors with concrete fix suggestions when input is malformed. Cheaper than notation_render — use this when iterating on input shape.

ParametersJSON Schema
NameRequiredDescriptionDefault
titleNo
composerNo
tempoNo
timeSignatureNo
keySignatureNo
instrumentsYes

TDQS

A4/5.0
Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Without annotations, the description carries the burden of disclosing behavior. It mentions it returns errors with fix suggestions and is cheaper, but does not explicitly state that the tool is read-only, idempotent, or free of side effects—common expectations for a validation tool but not confirmed. More explicit behavioral context would be beneficial.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two concise sentences. The first sentence states purpose and output; the second gives usage guidance. No repetition or filler. Essential information is front-loaded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the absence of annotations and output schema, the description covers purpose and usage but omits detail on error types, fix suggestion format, input limitations, or edge cases. It provides a minimal but functional level of completeness, with room for more context.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters2/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema has 6 parameters with 0% description coverage; the description adds no parameter-specific meaning. While parameter names (title, composer, tempo, etc.) are self-explanatory, the description fails to clarify constraints, relationships, or how parameters influence validation. This is a significant gap.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description explicitly states the tool validates an input shape without rendering, distinguishing it from the sibling notation_render. It uses specific verbs ('validate') and identifies the resource ('input shape'), making the purpose unmistakable.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides clear guidance: 'Cheaper than notation_render — use this when iterating on input shape.' It tells the agent when to use (during iteration) and implies an alternative (notation_render for actual rendering).

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections. Dates show when Glama detected each change.

  1. 1 tool update
    • Changedknowledge_search4 fields changed
      • addedInput schema / properties / limit / description
        Added value: +"Maximum chunks to return. Default 8 is right for most queries; raise for broad surveys, lower for tight context budgets."
      • addedInput schema / properties / maxTokens / description
        Added value: +"Token budget for the combined chunk content. Default 1500 fits comfortably in most agent context windows. The endpoint greedy-selects highest-similarity chunks within this budget."
      • changedInput schema / properties / step / description
        Previous value: -"Curriculum step number (1-49) as a fallback if you do not know the topic tag."New value: +"Curriculum step number (1-49). Fallback when you do not know the topic tag. Maps to the Gradus 10-stage curriculum: Stage I 1-7 (single voice, intervals, scales), II 8-13 (counterpoint, all 5 species), III 14-16 (harmony, third voice), IV 17-18 (form, modulation), V 19-20 (fugue), VI 21-25 (classical style, sonata), VII 26-30 (Romantic harmony, augmented sixths), VIII 31-33 (Impressionist), IX 34-36 (20th century), X 37-40 (advanced)."
      • changedInput schema / properties / topics / description
        Previous value: -"Topic tags in kebab-case. Examples: [\"voice-leading\",\"deceptive-cadence\"], [\"chromatic-mediants\"], [\"sonata-form\",\"second-theme\"]."New value: +"Topic tags in kebab-case. Matched semantically via Voyage 3 Large embeddings plus a topic-overlap boost; exact-match is not required, so close synonyms work. Examples: [\"voice-leading\",\"deceptive-cadence\"], [\"chromatic-mediants\"], [\"sonata-form\",\"second-theme\"], [\"figured-bass\",\"6-4-2-chord\"], [\"fugue\",\"stretto\"], [\"modulation\",\"pivot-chord\"]."
  2. 5 tool updatesv0.1.1
    • First observedknowledge_search
    • First observednotation_examples
    • First observednotation_render
    • First observednotation_schema
    • First observednotation_validate

TDQS

A4.2/5.0
Disambiguation5/5

Each tool has a clearly distinct purpose: knowledge_search for theory facts, notation_examples for example inputs, notation_render for rendering, notation_schema for schema retrieval, and notation_validate for input validation. There is no functional overlap.

Naming Consistency3/5

Tools use a mix of noun_verb (knowledge_search, notation_render, notation_validate) and noun_noun (notation_examples, notation_schema) patterns. Additionally, one tool deviates from the 'notation_' prefix ('knowledge_search'), reducing consistency.

Tool Count4/5

With 5 tools, the server is reasonably scoped for its purpose of music notation rendering and theory knowledge retrieval. It covers core functionality without being overly minimal or excessive.

Completeness4/5

The tool set covers search, retrieval of examples, input validation, schema access, and rendering. Minor potential gaps (e.g., no tool to list available examples or manage rendered outputs) are not critical for the stated domain.

Maintenance

ActivityMaintained
ResponsivenessUnresponsive

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