Excalidraw Agent Skill

Excalidraw Agent Skill

Use this skill when a user asks an Agent to create, update, inspect, review, or recover an Excalidraw drawing through the Xpert Excalidraw plugin.

The plugin has two surfaces:

• Workbench: the human review and editing surface. It can list drawings, edit the canvas, save versions, import/export JSON/PNG/SVG, convert Mermaid, restore versions, mark reviewed/draft, archive, and delete drawings or versions.
• Middleware tools: the Agent-callable system of record. These tools create drawing records, save scene versions, patch elements, save Mermaid drafts, search/read compact metadata, fetch exact scene items, update lifecycle status, and report failures.

Do not treat Workbench view actions as Agent middleware tools. Use only the middleware tool names documented below when acting from an Agent.

Core Rules

Before creating a new drawing, call excalidraw_list_typography_presets, choose a managed built-in preset, and use its returned fontFamilyId. Do not invent custom font ids or URLs.

1. Do not invent drawing ids, version ids, or element ids for existing drawings. Use Workbench context, excalidraw_search_drawings, excalidraw_get_drawing, or excalidraw_get_scene_item.
2. Prefer direct Excalidraw elements as the default creation path. Use Mermaid only when the user explicitly asks for Mermaid, provides Mermaid source, or wants a fast low-fidelity draft where exact layout and editability are less important.
3. If the rendered excalidrawDrawingId value or middleware-injected current Workbench context is present, update that current Workbench drawing. Do not call excalidraw_create_drawing for additions, blank-area insertions, title edits, restyling, or other updates to that drawing.
4. For new complex diagrams where no current drawing exists or the user explicitly asks for a new drawing, call excalidraw_create_drawing first, then call excalidraw_add_elements in one element or small logical batches. This gives the Workbench incremental updates and keeps failures easy to retry.
5. Before editing an existing drawing, call excalidraw_get_drawing first unless the current prompt already contains a trustworthy Workbench context with the drawing id and version ref.
6. Prefer excalidraw_patch_scene for targeted edits. Use excalidraw_save_scene_version only when a full scene replacement is intentional.
7. Use excalidraw_get_drawing for compact metadata and lightweight refs. Use excalidraw_get_scene_item for full element JSON, full appState, file payloads, or full Mermaid source.
8. Keep changes small and reviewable. Use short changeSummary values that describe the operation, not a long user-visible answer.
9. Do not claim a drawing was saved unless the tool call succeeded. Tool results are the source of truth.
10. Do not route logic from display text, localized labels, sample titles, or incidental field combinations. Use explicit fields such as selection.type, itemType, kind, status, and sourceType.

Default Tool Choice

Choose the tool path in this order:

1. Current Workbench drawing update: use rendered excalidrawDrawingId or the middleware-injected current Workbench context -> excalidraw_get_drawing -> excalidraw_add_elements, excalidraw_patch_scene, or excalidraw_save_scene_version.
2. New editable diagram when no current drawing exists or the user explicitly asks for a new drawing: excalidraw_create_drawing -> repeated excalidraw_add_elements.
3. Existing drawing targeted edit by explicit id or search result: excalidraw_get_drawing -> optional excalidraw_get_scene_item -> excalidraw_patch_scene.
4. Intentional full replacement: excalidraw_save_scene_version.
5. Explicit Mermaid import/draft: excalidraw_save_mermaid_draft.
6. Failure or unresolved context: excalidraw_report_failure.

Do not choose Mermaid just because the diagram is a flowchart or architecture map. The plugin can create editable boxes, labels, arrows, groups, frames, and containers directly with Excalidraw elements, and that should be the default.

Workbench Selection Context

The Workbench automatically sends assistant.context.set when the user opens a drawing or changes the canvas selection. The payload goes into runtime context/env for the Agent run. Middleware also reads that runtime context directly and can inject the current drawingId into Excalidraw tools when the tool call omits it.

The assistant prompt may render runtime env values as plain field-name lines. Reason from those visible names and values, not from JavaScript-style paths such as env.excalidrawDrawingId, and not from persistent state variable names.

When the prompt includes these rendered field names, use them before searching broadly:

• excalidrawDrawingId
• excalidrawVersionId
• excalidrawVersionNumber
• excalidrawSelectedElementIdsJson
• excalidrawSelectionJson
• excalidrawContextJson
• excalidrawSceneDirty

Template stateVariables are not required for these Workbench values. Older state names such as currentDrawingId/currentVersionId are not the source of truth.

If rendered excalidrawDrawingId is non-empty, treat it as the current Workbench drawing even when no elements are selected. If rendered excalidrawContextJson is non-empty, parse it as JSON for extra metadata. The expected shape is:

{
  "currentDrawing": {
    "drawingId": "drawing-id",
    "title": "Drawing title",
    "currentVersionId": "version-id",
    "currentVersionNumber": 12,
    "isDirty": true,
    "source": "@xpert-ai/plugin-excalidraw",
    "selection": {
      "type": "excalidraw.selection.v1",
      "selectedElementIds": ["element-id"],
      "selectedElementCount": 1,
      "elements": [
        {
          "id": "element-id",
          "type": "rectangle",
          "x": 10,
          "y": 20,
          "width": 200,
          "height": 80,
          "textPreview": "optional text",
          "groupIds": ["group-id"],
          "containerId": "container-id",
          "boundElementIds": ["arrow-id"]
        }
      ],
      "bounds": { "x": 10, "y": 20, "width": 200, "height": 80 },
      "capturedAt": "2026-06-21T15:22:28.459Z"
    }
  }
}

Selection rules:

• currentDrawing may exist without selection; this means a drawing is open but no element is selected. Use the rendered excalidrawDrawingId or the middleware-injected current Workbench context for additions such as "add this in the blank area".
• Treat currentDrawing.selection.type === "excalidraw.selection.v1" as the only valid machine-readable selection discriminator.
• If a valid selection exists, modify only selectedElementIds unless the user explicitly asks to affect neighboring or unselected elements.
• Use compact selection.elements only for orientation, bounds, and intent. Fetch full element JSON with excalidraw_get_scene_item before changing exact geometry, style, bindings, text, or file-backed elements.
• If currentDrawing.isDirty === true or rendered excalidrawSceneDirty is true, the compact selected refs may include unsaved canvas state newer than the persisted current version. Use the refs to understand the user intent, then fetch persisted JSON before patching. If the selected id is missing in the persisted version, ask the user to save the Workbench version or explain that the unsaved element cannot be patched by middleware yet.
• If no valid selection context exists but the user asks to edit "the selected element", ask them to select an element or provide a drawing id and element id.

Tool Contracts

excalidraw_create_drawing

Create a managed drawing metadata record.

Inputs:

• Required: title.
• Optional: description, kind, tags, source, changeSummary.
• kind is one of diagram, whiteboard, flowchart, architecture, wireframe, other.

Rules:

• Do not call this when rendered excalidrawDrawingId or middleware-injected context identifies the current Workbench drawing and the user is asking to add, edit, or place content in that drawing.
• This middleware schema is metadata-only. Do not pass elements, appState, files, or mermaidSource.
• After success, call excalidraw_add_elements, excalidraw_save_scene_version, or excalidraw_save_mermaid_draft with the returned drawingId.

excalidraw_add_elements

Append valid full Excalidraw elements to an existing drawing.

Inputs:

• Required: elements.
• Optional: drawingId, appStatePatch, files, mermaidSource, changeSummary.
• Omit drawingId only when operating on the current Workbench drawing identified by rendered excalidrawDrawingId or middleware-injected context.
• elements must contain 1 to 20 full element objects.

Rules:

• Prefer 1 to 5 logically related elements per call for complex diagrams.
• This tool routes through the same strict patch path as excalidraw_patch_scene.
• Added element ids must be unique and must not already exist in the current scene.
• Omit files unless adding or replacing file-backed assets. If provided, it replaces the current files map.

excalidraw_save_scene_version

Save a complete valid Excalidraw scene as a new version.

Inputs:

• Required: drawingId unless operating on the current Workbench drawing.
• Optional: elements, appState, files, mermaidSource, sourceType, changeSummary.
• sourceType is one of agent_json, agent_patch, agent_mermaid, workbench, workbench_mermaid, import, restore; Agent full JSON should normally use agent_json.

Rules:

• Use this only for intentional full replacement or full-scene creation after a drawing record exists.
• Read the current drawing first if user edits may exist.
• Preserve appState, files, and mermaidSource from the current version when they should remain unchanged. This tool saves the scene you provide as the new version.

excalidraw_patch_scene

Apply strict add/update/delete changes to the current drawing version and save a new agent_patch version.

Inputs:

• Required: at least one change field such as addElements, updateElements, deleteElementIds, appStatePatch, files, or mermaidSource.
• Optional: drawingId, addElements, updateElements, deleteElementIds, appStatePatch, files, mermaidSource, changeSummary.
• Omit drawingId only when operating on the current Workbench drawing identified by rendered excalidrawDrawingId or middleware-injected context.
• Each updateElements item must include id plus shallow fields to merge onto the current element.

Rules:

• Unknown update ids, unknown delete ids, duplicate added ids, type changes, invalid elements, and no-op patches are rejected.
• updateElements is shallow. Include only fields that should change, but never change type.
• deleteElementIds deletes elements from the scene version; use it only when the user asks to remove those elements.
• appStatePatch shallow-merges into current appState.
• Omit files unless replacing the files map intentionally. If provided, it replaces the current files map.
• Patches always target the current version, not an arbitrary older version.

excalidraw_save_mermaid_draft

Save Mermaid source for Workbench conversion and review.

Inputs:

• Required: mermaidSource.
• Required when creating a new drawing: title.
• Optional: drawingId, description, kind, changeSummary.
• Omit drawingId only when saving to the current Workbench drawing or intentionally creating a new Mermaid draft because no current drawing exists.

Rules:

• Use this when the user explicitly asks for Mermaid, provides Mermaid source, or asks for a quick draft where exact layout and editability are less important.
• Do not use this as the default path for architecture diagrams, product maps, whiteboards, UI sketches, or diagrams that should be deliberately laid out.
• Flowcharts usually convert to editable Excalidraw elements best, but direct Excalidraw elements are still preferred for new editable drawings.
• Other Mermaid diagram types may convert as image-like content and may be less editable; warn the user when editability matters.
• After the tool succeeds, the Workbench can auto-convert the Mermaid draft and save an editable Excalidraw version.

excalidraw_search_drawings

Find existing drawings.

Inputs:

• Optional: status, kind, search, page, pageSize.
• status is one of draft, reviewed, archived.
• pageSize max is 100.

Rules:

• Returns drawing metadata only, not scene JSON.
• Use when the user refers to a drawing by title, topic, or status and no drawing id is available.

excalidraw_get_drawing

Read compact drawing metadata, current version ref, lightweight version refs, optional action log metadata, and optional paged lightweight element refs.

Inputs:

• Required: drawingId unless reading the current Workbench drawing.
• Optional: includeScene, versionId, versionNumber, versionLimit, includeLogs, logLimit, elementOffset, elementLimit.
• versionLimit and logLimit max are 20.
• elementLimit max is 200.
• includeFiles is deprecated; use excalidraw_get_scene_item with itemType=file.

Rules:

• Default output is compact and intentionally avoids full scene JSON.
• Set includeScene=true only to page lightweight element refs for a selected version.
• Lightweight element refs include fields such as id, type, geometry, textPreview, file/container/frame/group refs, points count, and bound element ids.
• Use returned currentVersion, requestedVersion, versions, and nextActions to choose follow-up reads.

excalidraw_get_scene_item

Fetch one explicit full scene item from a drawing version.

Inputs:

• Required: itemType.
• Required: drawingId unless reading the current Workbench drawing.
• Optional: versionId, versionNumber, elementId, fileId.
• itemType is one of element, appState, file, mermaidSource.

Rules:

• For itemType=element, provide elementId.
• For itemType=file, provide fileId.
• Omit versionId and versionNumber to read the current version.
• Use this before exact selected-element edits, image/file edits, binding edits, text edits, or full Mermaid inspection.

excalidraw_update_drawing_status

Update a drawing lifecycle status.

Inputs:

• Required: status.
• Required: drawingId unless updating the current Workbench drawing.
• Optional: reason.
• status is one of draft, reviewed, archived.

Rules:

• Mark reviewed only after user or workflow confirmation.
• Use archived for Agent-side lifecycle removal. Physical drawing/version deletion is a Workbench action, not a middleware tool.

excalidraw_report_failure

Record a failed generation, conversion, import, inspection, or patch attempt.

Inputs:

• Required: operation, errorMessage.
• Optional: drawingId, versionId, recoverable, evidence.

Rules:

• Call this when source material is missing, Mermaid is invalid, JSON cannot be made valid, selected elements cannot be resolved, or the requested edit conflicts with the current persisted drawing.
• Include concise evidence such as tool error text, invalid ids, parse issue, or the relevant request fragment.

Recommended Workflows

New editable Excalidraw drawing

Use this workflow only when there is no current Workbench drawing id or the user explicitly asked for a new/separate drawing.

1. Call excalidraw_create_drawing with title, optional kind, tags, and a short changeSummary.
2. Plan a stable coordinate system before adding elements. Leave comfortable spacing for labels and connectors.
3. Add containers, frames, or major regions first with excalidraw_add_elements.
4. Add nodes and text labels in small logical batches.
5. Add arrows/connectors after both endpoints exist. Keep arrow ids stable and use supported arrowhead values.
6. Use excalidraw_get_drawing with includeScene=true to page lightweight refs for verification when needed.
7. Use excalidraw_patch_scene for final targeted corrections.

New Mermaid draft

1. Use this only when Mermaid is explicitly requested, Mermaid source is supplied, or speed matters more than exact editable layout.
2. Call excalidraw_save_mermaid_draft with title, kind, mermaidSource, and changeSummary.
3. Tell the user the draft was saved for Workbench conversion and review.
4. For follow-up edits, inspect the converted version with excalidraw_get_drawing and excalidraw_get_scene_item, then patch with direct Excalidraw elements.

Update an existing drawing

1. Resolve the drawing id from rendered excalidrawDrawingId, middleware-injected current context, user input, tool results, or excalidraw_search_drawings.
2. Call excalidraw_get_drawing for compact metadata.
3. If ids or geometry are needed, call excalidraw_get_drawing with includeScene=true, versionId or versionNumber, and pagination.
4. Fetch exact items with excalidraw_get_scene_item.
5. Apply excalidraw_patch_scene for targeted edits or excalidraw_save_scene_version for an intentional full replacement.

Edit the current Workbench selection

1. Parse rendered excalidrawContextJson.
2. Verify currentDrawing.selection.type === "excalidraw.selection.v1".
3. Use rendered excalidrawDrawingId; use version metadata from parsed excalidrawContextJson only when needed.
4. For each selected id that needs exact changes, call excalidraw_get_scene_item with itemType=element.
5. Build an excalidraw_patch_scene request that only changes selected ids unless the user explicitly broadened scope.
6. If the scene is dirty and selected ids are not in the persisted version, ask the user to save the Workbench version or report a recoverable failure.

Add to the current Workbench drawing with no selection

1. Read rendered excalidrawDrawingId.
2. Call excalidraw_get_drawing for compact metadata and, when placement depends on existing contents, page lightweight refs with includeScene=true.
3. Add new elements to that same drawing with excalidraw_add_elements or excalidraw_patch_scene.
4. If the user says "blank area" but no coordinates are available, choose a clear empty region based on the current scene bounds; do not create a new drawing.

Inspect a large scene

1. Call excalidraw_get_drawing without includeScene first.
2. Page lightweight refs with includeScene=true, elementOffset, and elementLimit.
3. Fetch only the exact full elements/files/appState/Mermaid source needed with excalidraw_get_scene_item.
4. Avoid loading many full scene items unless the task requires it.

Excalidraw Element Rules

• Persist only supported element types: rectangle, diamond, ellipse, arrow, line, freedraw, text, image, frame, magicframe, iframe, embeddable.
• Never persist transient selection elements.
• Use stable, semantic ids such as box-api-gateway, text-api-gateway, and arrow-api-to-service. Avoid random-looking ids unless preserving imported elements.
• Build diagrams in layers: background regions or frames, primary nodes, text labels, connectors, then annotations and highlights.
• Prefer separate text elements for labels inside important boxes when exact placement matters; use container binding only when the label should move tightly with a shape.
• Keep coordinates, widths, and heights explicit. Leave extra width for Chinese labels and multi-line text.
• Use consistent colors and stroke widths per region. Avoid making every item a separate palette unless the user's domain calls for it.
• Every element needs a non-empty id, explicit type, finite common geometry/style/version fields, isDeleted, locked, groupIds, and binding fields expected by Excalidraw.
• Common required string fields include strokeColor, backgroundColor, fillStyle, and strokeStyle.
• Common required number fields include x, y, width, height, angle, strokeWidth, roughness, opacity, seed, version, versionNonce, and updated.
• The service normalizes missing/invalid updated and invalid index values, but do not rely on invented order keys. Use index: null or omit index unless copying a valid order key from an existing scene.
• Text elements require fields such as fontSize, fontFamily, text, originalText, textAlign, verticalAlign, containerId, autoResize, and lineHeight.
• Arrow and line elements require points, bindings, arrowheads, and elbowed for arrows.
• Freedraw elements require points, pressures, simulatePressure, and lastCommittedPoint.
• Image elements require status, scale, crop, and a fileId that exists in the files map when non-empty.
• Keep appStatePatch, files, and mermaidSource omitted unless the change really needs them, so user state and assets are not overwritten accidentally.

Response Style

Keep user-facing responses concise. State what was saved or patched, which drawing/version was affected when useful, and what the user can review next in the Workbench. If a tool failed or the selected element could not be resolved, explain the blocker and the smallest useful recovery step.

Native MCP and recovery

MCP calls require explicit drawingId for existing drawings and a stable operationId for mutations. Reuse an operationId only with identical input. Read the scene revision for scene replacement/restore, and the IR revision for technical edits; diagram_validate writes a new IR revision. save_scene_version updates the working scene; checkpoint_version freezes history.

Use create_preview or convert_mermaid for headless work. Persist jobId and cursor, use wait_job (up to 45 seconds per call) until terminal, and resume with get_job after reconnecting. Read PNG content with read_preview before visual review. DiagramIR quality images carry their IR revision and can differ from the actual scene. A conversion conflict retains its result for read_export and never overwrites current work.

All Excalidraw tools, including public sharing, declare direct invocation under application policy. Do not request host.input confirmation or send a confirmation boolean. Public links still require an explicit drawingId, expectedRevision and operationId; stale revisions must fail. Use only platform Artifact URLs and revoke with revoke_artifact_link.

excalidraw_diagram_render requires both expectedRevision (DiagramIR) and expectedSceneRevision (canvas) over MCP. Read the drawing again before replacing the scene.

Tool results are compact DTOs. Drawing summaries are flat (drawingId, sceneRevision, versionNumber); read history with list_versions. diagram_get returns ir without quality history. Read paged issues with diagram_get_quality_report (issueOffset/issueLimit, reviewOffset/reviewLimit). Export metadata appears only in the first chunk. Do not expect entity fields, data/item wrappers on parent reads, or echoed input.

Tool DTOs are available as JSON text as well as structuredContent. Read returned IDs/revisions/URLs directly; no shell fallback is needed for text-only clients. Use validation issue paths or targetIds to repair the reported defects. Follow nextIssueOffset with diagram_get_quality_report for persisted reports; a failed create has no report to read. Retain changedIds for subsequent scene edits and the effective review decision/attempt for the correction limit.

Tool output recovery: resultStatus: "unavailable" means the detailed result could not be prepared. Preserve the known business status and IDs; read the returned drawing/job or retry identical arguments with the same operationId. Do not start a new write to recover a missing response.