MCP Avantage

Instructions

Implementation Reference

• src/index.ts:1194-1208 (registration)

  Registers the MCP tool 'technicalIndicators_htDcphase' with name, description, input schema, and an inline execute handler that delegates to the generic executeAvantageTool with the specific AVantage library method.

  server.addTool({
    name: "technicalIndicators_htDcphase",
    description: "Hilbert Transform - Dominant Cycle Phase",
    parameters: schemas.TechnicalIndicatorsHtDcphaseParamsSchema,
    execute: (
      args,
      context // Let type be inferred
    ) =>
      executeAvantageTool(
        "technicalIndicators_htDcphase",
        args,
        context,
        (av, params) => av.technicalIndicators.htDcphase(params)
      ),
  });

• src/schemas.ts:235-235 (schema)

  Zod schema definition for the tool's input parameters, extending the common technical indicator params with series_type.

  export const TechnicalIndicatorsHtDcphaseParamsSchema = TechnicalIndicatorsCommonIndicatorParamsSchema.extend({ series_type: SeriesTypeSchema }).describe('Parameters for HT_DCPHASE.');

• src/index.ts:38-115 (helper)

  Generic helper function used by all tools, including this one, to execute the AVantage library method. Manages authentication, caching of AVantage instances, calls the specific indicator method, and formats the response.

  async function executeAvantageTool<TArgs, TResult>(
    toolName: string,
    args: TArgs,
    context: Context<Record<string, unknown> | undefined>, // Use the imported Context type directly
    avantageMethod: (
      av: AVantage,
      args: TArgs
    ) => Promise<{ error?: boolean; reason?: string; data?: TResult }>
  ): Promise<string> {
    logger.info(`Executing '${toolName}' tool for request ID: ${context}`);
    logger.debug(`Args for ${toolName}: ${JSON.stringify(args)}`);
  
    // --- Authentication & Resource Management ---
    // Access extraArgs safely - it might be null or undefined
    const extraArgsApiKey = context.extraArgs?.apiKey as string | undefined;
    const apiKey = extraArgsApiKey || config.apiKey;
  
    if (!apiKey) {
      logger.error(`'${toolName}' failed: Alpha Vantage API key missing.`);
      throw new UserError(apiKeyErrorMessage);
    }
    logger.debug(
      `Using AV API key (source: ${extraArgsApiKey ? "extraArgs" : "environment"}) for ${toolName}`
    );
  
    try {
      // Get or create AVantage instance managed by ResourceManager
      const av = await resourceManager.getResource<AVantage>(
        apiKey, // Cache key is the resolved API key
        "avantage_client", // Type identifier for logging
        async (key) => {
          // Factory Function
          logger.info(
            `Creating new AVantage instance for key ending ...${key.slice(-4)}`
          );
          // AVantage library reads AV_PREMIUM from process.env internally
          return new AVantage(key);
        },
        async (avInstance) => {
          // Cleanup Function (no-op needed for AVantage)
          logger.debug(`Destroying AVantage instance (no-op)`);
        }
      );
  
      // --- Library Call ---
      const result = await avantageMethod(av, args);
  
      // --- Response Handling ---
      if (result.error) {
        logger.warn(
          `'${toolName}' failed. Reason from avantage: ${result.reason}`
        );
        throw new UserError(result.reason || `Tool '${toolName}' failed.`);
      }
  
      if (result.data === undefined || result.data === null) {
        logger.warn(`'${toolName}' completed successfully but returned no data.`);
        return "null"; // Return string "null" for empty data
      }
  
      logger.info(`'${toolName}' completed successfully.`);
      // Stringify the data part of the response
      return JSON.stringify(result.data);
    } catch (error: any) {
      logger.error(
        `Error during execution of '${toolName}': ${error.message}`,
        error
      );
      // If it's already a UserError, rethrow it
      if (error instanceof UserError) {
        throw error;
      }
      // Otherwise, wrap it in a UserError
      throw new UserError(
        `An unexpected error occurred while executing tool '${toolName}': ${error.message}`
      );
    }
  }

• src/index.ts:1198-1207 (handler)

  The specific execute handler for the tool, which passes the tool name, args, context, and the AVantage method av.technicalIndicators.htDcphase to the generic executor.

  execute: (
    args,
    context // Let type be inferred
  ) =>
    executeAvantageTool(
      "technicalIndicators_htDcphase",
      args,
      context,
      (av, params) => av.technicalIndicators.htDcphase(params)
    ),