MCP Server Chart

Instructions

Implementation Reference

• src/utils/callTool.ts:44-111 (handler)

  Generic handler function that executes the logic for generate_network_graph by mapping to chart type 'network-graph', validating input schema, and calling generateChartUrl to produce the 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/network-graph.ts:14-40 (schema)

  Zod-based input schema for the generate_network_graph tool, defining data (nodes/edges), optional style, theme, width, and height.

  const schema = {
    data: z
      .object({
        nodes: z
          .array(NodeSchema)
          .nonempty({ message: "At least one node is required." }),
        edges: z.array(EdgeSchema),
      })
      .describe(
        "Data for network graph chart, such as, { nodes: [{ name: 'node1' }, { name: 'node2' }], edges: [{ source: 'node1', target: 'node2', name: 'edge1' }] }",
      )
      .refine(validatedNodeEdgeDataSchema, {
        message: "Invalid parameters",
        path: ["data", "edges"],
      }),
    style: z
      .object({
        texture: TextureSchema,
      })
      .optional()
      .describe(
        "Style configuration for the chart with a JSON object, optional.",
      ),
    theme: ThemeSchema,
    width: WidthSchema,
    height: HeightSchema,
  };

• src/charts/network-graph.ts:43-52 (registration)

  Tool descriptor object containing name, description, inputSchema, and annotations, exported and used in tools/list response.

  const tool = {
    name: "generate_network_graph",
    description:
      "Generate a network graph chart to show relationships (edges) between entities (nodes), such as, relationships between people in social networks.",
    inputSchema: zodToJsonSchema(schema),
    annotations: {
      title: "Generate Network Graph",
      readOnlyHint: true,
    },
  };

• src/utils/callTool.ts:9-36 (helper)

  Mapping from tool names like 'generate_network_graph' to internal chart types like 'network-graph' used in the handler.

  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;

• src/utils/generate.ts:12-39 (helper)

  Core function that generates the chart URL by posting the chart type ('network-graph') and options to the external visualization service.

  export async function generateChartUrl(
    type: string,
    // biome-ignore lint/suspicious/noExplicitAny: <explanation>
    options: Record<string, any>,
  ): Promise<string> {
    const url = getVisRequestServer();
  
    const response = await axios.post(
      url,
      {
        type,
        ...options,
        source: "mcp-server-chart",
      },
      {
        headers: {
          "Content-Type": "application/json",
        },
      },
    );
    const { success, errorMessage, resultObj } = response.data;
  
    if (!success) {
      throw new Error(errorMessage);
    }
  
    return resultObj;
  }

• src/server.ts:66-68 (registration)

  MCP tools/list request handler that returns the list of available tools, including generate_network_graph from the Charts exports.

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