MCP Server Chart

Instructions

Implementation Reference

• src/server.ts:71-75 (handler)

  MCP server request handler for tools/call, which receives the tool name (e.g. generate_area_chart) and arguments, and dispatches to callTool.

  server.setRequestHandler(CallToolRequestSchema, async (request: any) => {
    logger.info("calling tool", request.params.name, request.params.arguments);
  
    return await callTool(request.params.name, request.params.arguments);
  });

• src/utils/callTool.ts:44-110 (handler)

  Core tool execution logic: maps tool name to chart type (generate_area_chart -> 'area'), validates args against area schema, generates and returns chart URL.

  export async function callTool(tool: string, args: object = {}) {
    logger.info(`Calling tool: ${tool}`);
    const chartType = CHART_TYPE_MAP[tool as keyof typeof CHART_TYPE_MAP];
  
    if (!chartType) {
      logger.error(`Unknown tool: ${tool}`);
      throw new McpError(ErrorCode.MethodNotFound, `Unknown tool: ${tool}.`);
    }
  
    try {
      // Validate input using Zod before sending to API.
      // Select the appropriate schema based on the chart type.
      const schema = Charts[chartType].schema;
  
      if (schema) {
        // Use safeParse instead of parse and try-catch.
        const result = z.object(schema).safeParse(args);
        if (!result.success) {
          logger.error(`Invalid parameters: ${result.error.message}`);
          throw new McpError(
            ErrorCode.InvalidParams,
            `Invalid parameters: ${result.error.message}`,
          );
        }
      }
  
      const isMapChartTool = [
        "generate_district_map",
        "generate_path_map",
        "generate_pin_map",
      ].includes(tool);
  
      if (isMapChartTool) {
        // For map charts, we use the generateMap function, and return the mcp result.
        const { metadata, ...result } = await generateMap(tool, args);
        return result;
      }
  
      const url = await generateChartUrl(chartType, args);
      logger.info(`Generated chart URL: ${url}`);
  
      return {
        content: [
          {
            type: "text",
            text: url,
          },
        ],
        _meta: {
          description:
            "This is the chart's spec and configuration, which can be renderred to corresponding chart by AntV GPT-Vis chart components.",
          spec: { type: chartType, ...args },
        },
      };
      // biome-ignore lint/suspicious/noExplicitAny: <explanation>
    } catch (error: any) {
      logger.error(
        `Failed to generate chart: ${error.message || "Unknown error"}.`,
      );
      if (error instanceof McpError) throw error;
      if (error instanceof ValidateError)
        throw new McpError(ErrorCode.InvalidParams, error.message);
      throw new McpError(
        ErrorCode.InternalError,
        `Failed to generate chart: ${error?.message || "Unknown error."}`,
      );
    }

• src/charts/area.ts:24-58 (schema)

  Zod schema defining the input parameters and validation for the generate_area_chart tool.

  const schema = {
    data: z
      .array(data)
      .describe(
        "Data for area chart, it should be an array of objects, each object contains a `time` field and a `value` field, such as, [{ time: '2015', value: 23 }, { time: '2016', value: 32 }], when stacking is needed for area, the data should contain a `group` field, such as, [{ time: '2015', value: 23, group: 'A' }, { time: '2015', value: 32, group: 'B' }].",
      )
      .nonempty({ message: "Area chart data cannot be empty." }),
    stack: z
      .boolean()
      .optional()
      .default(false)
      .describe(
        "Whether stacking is enabled. When enabled, area charts require a 'group' field in the data.",
      ),
    style: z
      .object({
        backgroundColor: BackgroundColorSchema,
        palette: PaletteSchema,
        texture: TextureSchema,
        lineWidth: z
          .number()
          .optional()
          .describe("Line width for the lines of chart, such as 4."),
      })
      .optional()
      .describe(
        "Style configuration for the chart with a JSON object, optional.",
      ),
    theme: ThemeSchema,
    width: WidthSchema,
    height: HeightSchema,
    title: TitleSchema,
    axisXTitle: AxisXTitleSchema,
    axisYTitle: AxisYTitleSchema,
  };

• src/server.ts:66-68 (registration)

  MCP tools/list request handler that returns the list of available tools, including the descriptor for generate_area_chart from Charts.area.tool.

  server.setRequestHandler(ListToolsRequestSchema, async () => ({
    tools: getEnabledTools().map((chart) => chart.tool),
  }));

• src/utils/callTool.ts:9-36 (helper)

  Mapping of tool names to internal chart types; generate_area_chart maps to 'area' for use in Charts[chartType] and generateChartUrl.

  const CHART_TYPE_MAP = {
    generate_area_chart: "area",
    generate_bar_chart: "bar",
    generate_boxplot_chart: "boxplot",
    generate_column_chart: "column",
    generate_district_map: "district-map",
    generate_dual_axes_chart: "dual-axes",
    generate_fishbone_diagram: "fishbone-diagram",
    generate_flow_diagram: "flow-diagram",
    generate_funnel_chart: "funnel",
    generate_histogram_chart: "histogram",
    generate_line_chart: "line",
    generate_liquid_chart: "liquid",
    generate_mind_map: "mind-map",
    generate_network_graph: "network-graph",
    generate_organization_chart: "organization-chart",
    generate_path_map: "path-map",
    generate_pie_chart: "pie",
    generate_pin_map: "pin-map",
    generate_radar_chart: "radar",
    generate_sankey_chart: "sankey",
    generate_scatter_chart: "scatter",
    generate_treemap_chart: "treemap",
    generate_venn_chart: "venn",
    generate_violin_chart: "violin",
    generate_waterfall_chart: "waterfall",
    generate_word_cloud_chart: "word-cloud",
  } as const;