vchart-mcp-server

Instructions

Implementation Reference

• src/server.ts:43-125 (handler)

  MCP call_tool request handler that implements execution for all chart tools by mapping the tool name to the corresponding chart module ("wordcloud_venn" for generate_wordcloud_venn), validating inputs with the schema, and calling generateChartByType.
  server.setRequestHandler(CallToolRequestSchema, async request => { const toolName = request.params.name; const chartType = Object.keys(Charts).find( key => (Charts as any)[key].tool.name === toolName ); if (!chartType) { throw new McpError( ErrorCode.MethodNotFound, `Unknown tool: ${request.params.name}.` ); } try { // Validate input using Zod before generating chart const args = request.params.arguments || {}; // Select the appropriate schema based on the chart type const schema = Charts[chartType as keyof typeof Charts].schema; if (schema) { const result = schema.safeParse(args); if (!result.success) { throw new McpError( ErrorCode.InvalidParams, `Invalid parameters: ${result.error.message}` ); } } const res = await generateChartByType(chartType, args); if (res && (res as any).spec) { return { content: [ { type: 'text', text: JSON.stringify((res as any).spec, null, 2), }, ], }; } if (res && (res as any).image) { return { content: [ { type: 'text', text: (res as any).image, }, ], }; } if (res && (res as any).html) { return { content: [ { type: 'text', text: (res as any).html, }, ], }; } return { content: [ { type: 'text', text: 'Failed to generate chart', }, ], }; } catch (error: any) { if (error instanceof McpError) { throw error; } throw new McpError( ErrorCode.InternalError, `Failed to generate chart: ${error?.message || 'Unknown error.'}` ); } });
• src/charts/wordcloud.ts:16-47 (schema)

  Zod input schema definition for the generate_wordcloud_venn tool, including parameters for data, fields, dimensions, styling, and chart type (wordcloud or venn).
  const schema = z.object({ output: ChartOutputSchema, // Output format/schema for the chart width: WidthSchema, // Chart width height: HeightSchema, // Chart height chartType: z.enum(["wordcloud", "venn"]), dataTable: z .array(z.any()) .describe("Data for the chart, e.g., [{ word: 'TEST', value: 10 }].") .nonempty({ message: "data cannot be empty." }), // Data array must not be empty colorField: z .string() .nonempty({ message: "The field for words or sets cannot be empty." }) .describe( "Specifies the field in the dataset that represents each word (for word clouds) or the set (for Venn diagrams). For Venn diagrams, use a comma-separated string to describe the set. This field must exist in the dataset." ), valueField: z .string() .describe( "Specifies the field representing the metric value. Required for Venn diagrams." ), chartTheme: ThemeSchema, // Chart theme title: TitleTextSchema, // Chart title subTitle: TitleSubTextSchema, // Chart subtitle titleOrient: TitleOrientSchema, // Title orientation background: BackgroundSchema, // Chart background colors: ColorsSchema, // Chart colors });
• src/server.ts:34-38 (registration)

  MCP list_tools request handler that registers all chart tools, including generate_wordcloud_venn, by returning their tool definitions from the Charts modules.
  server.setRequestHandler(ListToolsRequestSchema, async () => { return { tools: Object.values(Charts).map(chart => (chart as any).tool), }; });
• src/charts/wordcloud.ts:49-59 (registration)

  Tool metadata definition (name, description, inputSchema) and export as wordcloud_venn module for use in Charts namespace.
  const tool = { name: "generate_wordcloud_venn", description: "Generate a word cloud to visualize word frequency or importance, or a Venn diagram to show relationships such as intersections and unions between sets.", inputSchema: convertZodToJsonSchema(schema), }; export const wordcloud_venn = { schema, tool, };
• src/utils/generateChart.ts:42-202 (helper)

  Core chart generation utility function called by the handler, processes input options into VChart spec using generateChart from @visactor/generate-vchart library, renders to image/html/spec based on chartType (wordcloud_venn here) and handles axis, title, data field mapping.
  export async function generateChartByType(chartType: string, options: any) { const { title, subTitle, titleOrient, xAxisType, xAxisOrient, xAxisTitle, xAxisHasGrid, xAxisHasLabel, xAxisHasTick, yAxisType, yAxisOrient, yAxisTitle, yAxisHasGrid, yAxisHasLabel, yAxisHasTick, leftYAxisTitle, leftYAxisHasGrid, leftYAxisHasLabel, leftYAxisHasTick, rightYAxisTitle, rightYAxisHasGrid, rightYAxisHasLabel, rightYAxisHasTick, angleAxisTitle, angleAxisHasGrid, angleAxisHasLabel, angleAxisHasTick, angleAxisType, radiusAxisHasGrid, radiusAxisHasLabel, radiusAxisHasTick, radiusAxisType, radiusAxisTitle, output, width, height, ...res } = options; const opts = { ...res }; const titleObj = filterValidAttributes({ text: title, subText: subTitle, orient: titleOrient, }); const xAxisObj = filterValidAttributes({ type: xAxisType, orient: xAxisOrient, title: xAxisTitle, hasGrid: xAxisHasGrid, hasLabel: xAxisHasLabel, hasTick: xAxisHasTick, }); const yAxisObj = filterValidAttributes({ type: yAxisType, orient: yAxisOrient, title: yAxisTitle, hasGrid: yAxisHasGrid, hasLabel: yAxisHasLabel, hasTick: yAxisHasTick, }); const leftYAxisObj = filterValidAttributes({ title: leftYAxisTitle, hasGrid: leftYAxisHasGrid, hasLabel: leftYAxisHasLabel, hasTick: leftYAxisHasTick, }); const rightYAxisObj = filterValidAttributes({ title: rightYAxisTitle, hasGrid: rightYAxisHasGrid, hasLabel: rightYAxisHasLabel, hasTick: rightYAxisHasTick, }); const angleAxisObj = filterValidAttributes({ title: angleAxisTitle, hasGrid: angleAxisHasGrid, hasLabel: angleAxisHasLabel, hasTick: angleAxisHasTick, type: angleAxisType, }); const radiusAxisObj = filterValidAttributes({ hasGrid: radiusAxisHasGrid, hasLabel: radiusAxisHasLabel, hasTick: radiusAxisHasTick, type: radiusAxisType, title: radiusAxisTitle, }); const cell: Record<string, string> = {}; [ "xField", "yField", "colorField", "categoryField", "valueField", "wordField", "sizeField", "timeField", "sourceField", "targetField", "setsField", "radiusField", ].forEach((fieldName) => { if (isValid(options[fieldName])) { cell[fieldName.replace("Field", "")] = options[fieldName]; delete opts[fieldName]; } }); opts.cell = cell; if (!isEmpty(titleObj)) { opts.title = titleObj; } const axes = [ xAxisObj, yAxisObj, leftYAxisObj, rightYAxisObj, angleAxisObj, radiusAxisObj, ]; if (axes.some((axis) => !isEmpty(axis))) { opts.axes = axes.filter((axis) => !isEmpty(axis)); } const { spec } = generateChart(options.chartType ?? chartType, opts); if (!spec) { return null; } if (output === "spec") { if (isValid(width)) { spec.width = width; } if (isValid(height)) { spec.height = height; } return { spec: spec, }; } return gentrateChartImageOrHtml(output, spec, { width: `${width ?? 500}px`, height: `${height ?? 500}px`, }); }