Marketstack MCP Server

Instructions

Implementation Reference

• src/tools/financialInstruments/getEtfHoldings.ts:22-41 (handler)

  The main handler function that implements the get_etf_holdings tool logic. It constructs API parameters for the 'etfholdings' endpoint using the input ticker and optional dates, fetches data via MarketstackClient, and returns the response.

  const getEtfHoldingsHandler = async (input: Input, client: MarketstackClient): Promise<Output> => {
    try {
      const { ticker, date_from, date_to } = input;
  
      const apiRequestParams: MarketstackApiParams = {
        endpoint: 'etfholdings',
        ticker,
        ...(date_from && { date_from }), // Include if date_from is provided
        ...(date_to && { date_to }), // Include if date_to is provided
      };
  
      const data = await client.fetchApiData(apiRequestParams);
  
      return data;
    } catch (error: unknown) {
      console.error('getEtfHoldings tool error:', error);
      const message = error instanceof Error ? error.message : 'An unknown error occurred.';
      throw new Error(`getEtfHoldings tool failed: ${message}`);
    }
  };

• src/tools/financialInstruments/getEtfHoldings.ts:5-15 (schema)

  Zod-based input schema shape defining the parameters for the get_etf_holdings tool: required ticker and optional date_from/date_to.

  const getEtfHoldingsInputSchemaShape = {
    ticker: z.string().describe('To get results based on a ETF ticker.'),
    date_from: z
      .string()
      .optional()
      .describe('Filter results based on a specific timeframe by passing a from-date in `YYYY-MM-DD` format.'),
    date_to: z
      .string()
      .optional()
      .describe('Filter results based on a specific timeframe by passing an end-date in `YYYY-MM-DD` format.'),
  };

• src/tools/financialInstruments/index.ts:55-60 (registration)

  Registration of the get_etf_holdings tool with the MCP server using server.tool(), referencing the tool definition imported from getEtfHoldings.ts.

  server.tool(
    getEtfHoldingsTool.name,
    getEtfHoldingsTool.description,
    getEtfHoldingsTool.inputSchemaShape,
    wrapToolHandler((input) => getEtfHoldingsTool.handler(input, client))
  );

• src/tools/financialInstruments/getEtfHoldings.ts:51-56 (registration)

  Tool definition export that bundles name, description, schema, and handler for get_etf_holdings, used in higher-level registration.

  export const getEtfHoldingsTool: MarketstackToolDefinition = {
    name: 'get_etf_holdings',
    description: 'Get complete set of exchange-traded funds data based on the unique identifier code of an ETF.',
    inputSchemaShape: getEtfHoldingsInputSchemaShape,
    handler: getEtfHoldingsHandler,
  };