MCP Avantage

Instructions

Implementation Reference

• src/index.ts:1325-1339 (handler)

  Handler implementation for the 'technicalIndicators_aroonosc' tool. It defines the execute function which invokes the shared executeAvantageTool helper to call the Alpha Vantage library's technicalIndicators.aroonosc method with validated parameters.
  server.addTool({ name: "technicalIndicators_aroonosc", description: "Aroon Oscillator", parameters: schemas.TechnicalIndicatorsAroonOscParamsSchema, execute: ( args, context // Let type be inferred ) => executeAvantageTool( "technicalIndicators_aroonosc", args, context, (av, params) => av.technicalIndicators.aroonosc(params) ), });
• src/schemas.ts:239-245 (schema)

  Schema definition for the tool parameters. TechnicalIndicatorsAroonOscParamsSchema extends the common time period schema, requiring symbol, interval, time_period, and optional datatype/month.
  export const TechnicalIndicatorsTimePeriodOnlyParamsSchema = TechnicalIndicatorsCommonIndicatorParamsSchema.extend({ time_period: z.string().describe('Number of data points used to calculate the indicator.'), }).describe('Parameters for indicators requiring symbol, interval, and time_period.'); export const TechnicalIndicatorsNatrParamsSchema = TechnicalIndicatorsTimePeriodOnlyParamsSchema.describe('Parameters for NATR.'); export const TechnicalIndicatorsAroonParamsSchema = TechnicalIndicatorsTimePeriodOnlyParamsSchema.describe('Parameters for AROON.'); export const TechnicalIndicatorsAroonOscParamsSchema = TechnicalIndicatorsTimePeriodOnlyParamsSchema.describe('Parameters for AROONOSC.');
• src/index.ts:1325-1339 (registration)

  Registration of the tool with the MCP server using server.addTool, linking name, description, parameters schema, and execute handler.
  server.addTool({ name: "technicalIndicators_aroonosc", description: "Aroon Oscillator", parameters: schemas.TechnicalIndicatorsAroonOscParamsSchema, execute: ( args, context // Let type be inferred ) => executeAvantageTool( "technicalIndicators_aroonosc", args, context, (av, params) => av.technicalIndicators.aroonosc(params) ), });
• src/index.ts:38-115 (helper)

  Core helper function used by all tools, including this one, to manage authentication, AVantage client lifecycle via resourceManager, execute the library method, handle errors, and return JSON stringified 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}` ); } }