Time MCP Server

Instructions

Implementation Reference

• src/index.ts:192-201 (handler)

  Core function executing the timezone conversion logic using dayjs library.

  function convertTime(sourceTimezone: string, targetTimezone: string, time?: string) {
    const sourceTime = time ? dayjs(time).tz(sourceTimezone) : dayjs().tz(sourceTimezone);
    const targetTime = sourceTime.tz(targetTimezone);
    const formatString = 'YYYY-MM-DD HH:mm:ss';
    return {
      sourceTime: sourceTime.format(formatString),
      targetTime: targetTime.format(formatString),
      timeDiff: dayjs(targetTime).diff(dayjs(sourceTime), 'hours'),
    };
  }

• src/tools.ts:78-99 (schema)

  Tool definition with input schema for validating arguments.

  export const CONVERT_TIME: Tool = {
    name: 'convert_time',
    description: 'Convert time between timezones.',
    inputSchema: {
      type: 'object',
      properties: {
        sourceTimezone: {
          type: 'string',
          description: 'The source timezone. IANA timezone name, e.g. Asia/Shanghai',
        },
        targetTimezone: {
          type: 'string',
          description: 'The target timezone. IANA timezone name, e.g. Europe/London',
        },
        time: {
          type: 'string',
          description: 'Date and time in 24-hour format. e.g. 2025-03-23 12:30:00',
        },
      },
      required: ['sourceTimezone', 'targetTimezone', 'time'],
    },
  };

• src/index.ts:30-34 (registration)

  Registers the convert_time tool (via CONVERT_TIME) in the list of available tools for MCP.

  server.setRequestHandler(ListToolsRequestSchema, async () => {
    return {
      tools: [CURRENT_TIME, RELATIVE_TIME, DAYS_IN_MONTH, GET_TIMESTAMP, CONVERT_TIME, GET_WEEK_YEAR],
    };
  });

• src/index.ts:109-124 (handler)

  Dispatcher handler case for 'convert_time' tool that handles request, validates, calls core logic, and formats response.

  case 'convert_time': {
    if (!checkConvertTimeArgs(args)) {
      throw new Error(`Invalid arguments for tool: [${name}]`);
    }
    const { sourceTimezone, targetTimezone, time } = args;
    const { sourceTime, targetTime, timeDiff } = convertTime(sourceTimezone, targetTimezone, time);
    return {
      success: true,
      content: [
        {
          type: 'text',
          text: `Current time in ${sourceTimezone} is ${sourceTime}, and the time in ${targetTimezone} is ${targetTime}. The time difference is ${timeDiff} hours.`,
        },
      ],
    };
  }

• src/index.ts:240-251 (helper)

  Helper function for validating input arguments against the schema types.

  function checkConvertTimeArgs(args: unknown): args is { sourceTimezone: string, targetTimezone: string, time: string } {
    return (
      typeof args === 'object' &&
      args !== null &&
      'sourceTimezone' in args &&
      typeof args.sourceTimezone === 'string' &&
      'targetTimezone' in args &&
      typeof args.targetTimezone === 'string' &&
      'time' in args &&
      typeof args.time === 'string'
    );
  }