MCP Avantage

Instructions

Implementation Reference

• src/index.ts:138-153 (registration)

  Registers the MCP tool 'alphaIntelligence_topGainersLosers'. Specifies name, description, empty input schema (no parameters), and an execute handler that calls the generic 'executeAvantageTool' function passing a callback to invoke 'av.alphaIntelligence.topGainersLosers()' from the AVantage library.

  server.addTool({
    name: "alphaIntelligence_topGainersLosers",
    description:
      "Retrieves the top N gainers, losers, and most actively traded US tickers.",
    parameters: z.object({}), // No parameters needed
    execute: (
      args,
      context // Let type be inferred
    ) =>
      executeAvantageTool(
        "alphaIntelligence_topGainersLosers",
        args,
        context,
        (av) => av.alphaIntelligence.topGainersLosers()
      ),
  });

• src/index.ts:143-152 (handler)

  The execute handler for the tool, which delegates to the generic executeAvantageTool with the specific AVantage library method call 'av.alphaIntelligence.topGainersLosers()'.

  execute: (
    args,
    context // Let type be inferred
  ) =>
    executeAvantageTool(
      "alphaIntelligence_topGainersLosers",
      args,
      context,
      (av) => av.alphaIntelligence.topGainersLosers()
    ),

• src/index.ts:142-142 (schema)

  Input schema definition using Zod: an empty object, indicating the tool takes no parameters.

  parameters: z.object({}), // No parameters needed

• src/index.ts:38-115 (helper)

  Generic helper function shared by all tools. Manages AVantage client instances via resourceManager, resolves API key from config or extraArgs, executes the provided avantageMethod callback on the AVantage instance, handles errors, and returns the JSON-stringified result 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}`
      );
    }
  }