MCP Avantage

Instructions

Implementation Reference

• src/index.ts:1091-1101 (registration)

  Registers the MCP tool 'technicalIndicators_ad' (Chaikin A/D Line) with its input schema reference and execute handler that delegates to the shared executeAvantageTool helper and calls av.technicalIndicators.ad(params) from the Avantage library.

    name: "technicalIndicators_ad",
    description: "Chaikin A/D Line",
    parameters: schemas.TechnicalIndicatorsCommonIndicatorParamsSchema,
    execute: (
      args,
      context // Let type be inferred
    ) =>
      executeAvantageTool("technicalIndicators_ad", args, context, (av, params) =>
        av.technicalIndicators.ad(params)
      ),
  });

• src/schemas.ts:204-209 (schema)

  Zod schema defining input parameters for the tool: required symbol and interval, optional datatype (default json) and month.

  export const TechnicalIndicatorsCommonIndicatorParamsSchema = z.object({
    symbol: z.string().describe('The stock symbol (e.g., "IBM").'),
    interval: z.string().describe('Time interval (e.g., "daily", "60min", "weekly"). Check Alpha Vantage docs for valid intervals per indicator.'),
    datatype: DatatypeSchema.default('json').optional(),
    month: z.string().optional().describe('Specific month for intraday intervals (YYYY-MM format).'),
  }).describe('Common parameters for many technical indicators.')

• src/index.ts:38-115 (helper)

  Shared helper function used by the tool's handler to manage authentication, AVantage client instance via resourceManager, execute the library method, handle errors, and return JSON string of the data.

  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}`
      );
    }
  }