MCP Avantage

Instructions

Implementation Reference

• src/index.ts:776-790 (registration)

  Registers the MCP tool 'fundamentalData_companyOverview' with server.addTool(). Specifies description, input parameters schema from schemas.ts, and an inline execute handler that invokes the generic executeAvantageTool, passing a callback to call av.fundamentalData.companyOverview(params.symbol).
  server.addTool({ name: "fundamentalData_companyOverview", description: "Fetches company overview details. Premium endpoint.", parameters: schemas.FundamentalDataSymbolParamsSchema, execute: ( args, context // Let type be inferred ) => executeAvantageTool( "fundamentalData_companyOverview", args, context, (av, params) => av.fundamentalData.companyOverview(params.symbol) ), });
• src/schemas.ts:172-174 (schema)

  Zod schema defining the input parameters for fundamental data tools like companyOverview: requires a 'symbol' string (e.g., 'IBM'). Used in multiple tool registrations.
  export const FundamentalDataSymbolParamsSchema = z.object({ symbol: z.string().describe('The stock symbol (e.g., "IBM").'), }).describe('Parameter schema requiring only a stock symbol.')
• src/index.ts:38-115 (handler)

  Generic handler function shared across all tools. Manages authentication (API key from extraArgs or config), acquires AVantage instance via resourceManager, invokes the specific library method (e.g., av.fundamentalData.companyOverview), handles errors, and returns stringified data. This executes the core tool logic for 'fundamentalData_companyOverview'.
  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}` ); } }