GA4 MCP Server

Instructions

Implementation Reference

• src/tools/basic/getMetadata.ts:7-40 (handler)

  The core handler function that fetches and formats GA4 metadata (dimensions and metrics) from the API.

  export async function getMetadata(input: PropertyId): Promise<GetMetadataOutput> {
    const propertyId = getPropertyId(input.propertyId);
    const property = formatPropertyPath(propertyId);
  
    const client = getDataClient();
    const [response] = await client.getMetadata({
      name: `${property}/metadata`,
    });
  
    const dimensions: MetadataItem[] = [];
    const metrics: MetadataItem[] = [];
  
    // ディメンション情報を整形
    for (const dim of response.dimensions || []) {
      dimensions.push({
        apiName: dim.apiName || "",
        uiName: dim.uiName || "",
        description: dim.description || "",
        category: dim.category || "",
      });
    }
  
    // メトリクス情報を整形
    for (const metric of response.metrics || []) {
      metrics.push({
        apiName: metric.apiName || "",
        uiName: metric.uiName || "",
        description: metric.description || "",
        category: metric.category || "",
      });
    }
  
    return { dimensions, metrics };
  }

• src/types.ts:95-106 (schema)

  TypeScript interfaces defining the output structure (GetMetadataOutput) and MetadataItem for the get_metadata tool.

  // get_metadata
  export interface MetadataItem {
    apiName: string;
    uiName: string;
    description: string;
    category: string;
  }
  
  export interface GetMetadataOutput {
    dimensions: MetadataItem[];
    metrics: MetadataItem[];
  }

• src/server.ts:188-202 (registration)

  MCP tool registration including name, description, and input schema definition.

  {
    name: "get_metadata",
    description:
      "利用可能なディメンションとメトリクスの一覧を取得します。run_reportで使える項目を確認できます。",
    inputSchema: {
      type: "object" as const,
      properties: {
        propertyId: {
          type: "string",
          description: "GA4プロパティID（省略時は環境変数を使用）",
        },
      },
      required: [],
    },
  },

• src/server.ts:614-617 (registration)

  Dispatch handler in the server that calls the getMetadata function for the 'get_metadata' tool.

  case "get_metadata":
    return await getMetadata({
      propertyId: args.propertyId as string | undefined,
    });