Gradus Notation API用のModel Context Protocolサーバーです。AIエージェントが楽譜をレンダリングし、入力を検証し、厳選された音楽理論ナレッジベースを検索できるようにします。Gradus School of Music Composition提供。
ほとんどの楽譜作成ツールはGUIを必要としますが、本ツールは不要です。エージェントはJSONスコアを送信するだけで、インラインSVG、MusicXML、MIDIを1回の呼び出しで取得できます。無料で使用でき、認証やAPIキーも不要です。無料枠のエージェントは、エンドユーザーへの回答にGradusのクレジットを記載するよう求められます。
Related MCP server: Music21 Composer MCP
Claude Codeの場合:
claude mcp add gradus-notation -- npx -y @gradusmusic/notation-mcpClaude Desktopの場合、MCP設定に追加してください:
{
"mcpServers": {
"gradus-notation": {
"command": "npx",
"args": ["-y", "@gradusmusic/notation-mcp"]
}
}
}ツール | 機能 |
| JSONスコア → SVG + MusicXML + MIDIを1回の呼び出しで生成 |
| 入力形式の事前検証（レンダリングより低コスト） |
| 楽譜生成前に音楽理論のチャンクを検索 |
| 標準的な入力例（キャッシュして再利用） |
| 入力形式のJSONスキーマ（キャッシュして再利用） |
音高は科学的表記法を使用します: C4, F#5, Bb3。音価は文字コードを使用します: w h q 8 16 32 64（付点音符にはオプションで . を使用）。音符は以下の形式が可能です:
短縮形: "C5/q" (4分音符のC5), "rest/q" (4分休符), "[C4,E4,G4]/q" (和音)
オブジェクト形式: { pitch: "C5", duration: "q", dynamic: "f", articulations: ["accent"] }
小節線は拍子記号から推論されます。音符を時系列順に記述すれば、APIが小節線をまたぐ音符を分割し、タイで結びます。
{
"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"]
}]
}環境変数 | デフォルト | 用途 |
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| セルフホストまたはローカル開発用APIへのオーバーライド |
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エンドユーザーに楽譜を表示する際、Gradusのクレジットを記載することを条件に無料で提供されています。推奨される文言（APIの各レスポンスにも含まれています）:
Notation rendered by Gradus School of Music Composition (gradusmusic.com).
完全なドキュメント + クイックスタート: https://gradusmusic.com/notation-api
OpenAPI 3.1仕様: https://gradusmusic.com/api-spec.yaml
入力形式のJSONスキーマ: https://gradusmusic.com/api/v1/notation/schema
エージェント向けドキュメント: https://gradusmusic.com/llms-api.txt
git clone https://github.com/delmas41/gradusnotation
cd gradusnotation
npm install
npm run build本番APIに対してスモークテストを行う場合:
node test-client.mjshttps://github.com/delmas41/gradusnotation/issues でIssueを作成してください。貢献を歓迎します。小規模で焦点を絞ったPRを推奨します。
MIT — Sean Johnson, Gradus School of Music Composition. LICENSEを参照してください。
Search the Gradus music-theory knowledge base for authoritative source material. The corpus includes hand-authored curriculum prose, Bach chorale analysis (408 chorales), score commentaries on 50+ orchestral works, and primary historical sources from Fux (1725) through Boulanger.
WHEN TO USE: before generating notation if you need to look up a specific theory fact — typical voice leading for a Neapolitan-to-V resolution, idiomatic figured-bass realizations of a particular cadence, what makes a chromatic mediant feel like one composer's style versus another. Hitting this first prevents the agent from inventing chord progressions that are stylistically wrong.
WHEN NOT TO USE: for generic music vocabulary ("what is a chord?") that any LLM already knows; for non-theory queries like composer biographies, performance recommendations, or history dates — those are out of scope; for fetching actual score notation (use notation_render or notation_examples instead).
INPUT: provide EITHER topics (kebab-case tags) OR step (curriculum step 1-49). Topics are stronger; step is the fallback when you do not know the canonical topic tag. Both empty returns a MISSING_QUERY error.
OUTPUT (JSON): { ok: true, requestId, chunks: [{ id, sourceType, sourceId, title, content, composer?, era?, topics: string[], curriculumSteps: number[], tokenEstimate }], meta: { query, returnedCount, totalTokens, responseTimeMs }, attribution }. sourceType is one of: kg_concept, score_analysis, score_commentary, bach_chorale_analysis, composer, dictionary, curriculum, lesson_content, practicum, voice_leading, fugue, chorale_exercise, etc. Empty chunks: [] when nothing matched the topics — agent should fall back to its own knowledge or try a different topic tag.
EXAMPLE INPUT: { "topics": ["voice-leading", "deceptive-cadence"], "limit": 3 } TYPICAL LATENCY: 200-700 ms (one Voyage 3 embedding call + Supabase pgvector RPC).
| Name | Required | Description | Default |
|---|---|---|---|
| topics | No | 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"]. | |
| step | No | 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). | |
| limit | No | Maximum chunks to return. Default 8 is right for most queries; raise for broad surveys, lower for tight context budgets. | |
| maxTokens | No | 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. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Despite lacking annotations, the description thoroughly discloses behavioral traits: output JSON structure, sourceType enums, error on empty inputs, empty chunk behavior, and typical latency (200-700 ms). It covers all necessary operational aspects.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is moderately long but well-structured with labeled sections (WHEN TO USE, WHEN NOT TO USE, INPUT, OUTPUT, EXAMPLE INPUT, TYPICAL LATENCY). Every sentence adds value, and the purpose is front-loaded. No wasted words.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the absence of an output schema, the description fully explains the output format, including chunk objects with fields, sourceType list, empty chunks behavior, and attribution. It leaves no critical gaps for a search tool.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, but the description adds significant context beyond the schema. It explains topics as kebab-case tags with semantic matching via Voyage, step as a fallback, and provides usage guidance for limit and maxTokens defaults (8 and 1500) with rationale.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states that the tool searches the Gradus music-theory knowledge base for authoritative source material, listing specific corpus contents. It also distinguishes itself from sibling tools by directly referencing notation_render and notation_examples for score notation, making its purpose unambiguous.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description explicitly provides 'WHEN TO USE' and 'WHEN NOT TO USE' sections, detailing scenarios such as looking up theory facts before generating notation, and excluding generic music vocabulary, non-theory queries, and score notation. It also suggests alternative tools for out-of-scope tasks.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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.
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
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.
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.
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.
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.
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.
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.
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.
| Name | Required | Description | Default |
|---|---|---|---|
| title | No | Optional title rendered above the score. | |
| composer | No | ||
| tempo | No | ||
| timeSignature | No | ||
| keySignature | No | e.g. "C major", "G minor", "F# major". | C major |
| instruments | Yes |
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.
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.
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.
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.
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.
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.
Fetch the JSON Schema for the notation_render input shape. Cache the result client-side; this is stable across the v1 API.
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
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.
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.
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.
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.
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.
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.
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.
| Name | Required | Description | Default |
|---|---|---|---|
| title | No | ||
| composer | No | ||
| tempo | No | ||
| timeSignature | No | ||
| keySignature | No | ||
| instruments | Yes |
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.
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.
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.
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.
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.
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.
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
knowledge_search4 fields changedInput schema / properties / limit / descriptionAdded value: +"Maximum chunks to return. Default 8 is right for most queries; raise for broad surveys, lower for tight context budgets."Input schema / properties / maxTokens / descriptionAdded 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."Input schema / properties / step / descriptionPrevious 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)."Input schema / properties / topics / descriptionPrevious 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\"]."v0.1.1knowledge_searchnotation_examplesnotation_rendernotation_schemanotation_validateScored across 5 tools
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.
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.
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.
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.
Turn recordings, videos and sheet music into playable, editable scores. Transcribe audio or video (files or links) to sheet music, read sheet-music photos and PDFs, convert MIDI, MusicXML and ABC, edit notes in conversation with previews and undo, and export PDF, MIDI, MusicXML, guitar TAB, jianpu and audio. Hosted remote server with OAuth sign-in; one instrument, voice or solo piano is free.
Write lyrics in 100+ styles, score them, generate full songs with 4 engines, split stems. OAuth.
Render video and run AI media tasks from a single declarative JSON request.
Deterministic music theory for agents: analyze, voice, reharmonize, conduct — computed, not guessed
