/**
* Logger utility for structured logging
*/
export enum LogLevel {
ERROR = 'ERROR',
WARN = 'WARN',
INFO = 'INFO',
DEBUG = 'DEBUG'
}
interface LogEntry {
timestamp: string;
level: LogLevel;
message: string;
data?: any;
}
class Logger {
private logLevel: LogLevel;
constructor(logLevel: LogLevel = LogLevel.INFO) {
this.logLevel = logLevel;
}
private shouldLog(level: LogLevel): boolean {
const levels = [LogLevel.ERROR, LogLevel.WARN, LogLevel.INFO, LogLevel.DEBUG];
return levels.indexOf(level) <= levels.indexOf(this.logLevel);
}
private log(level: LogLevel, message: string, data?: any): void {
if (!this.shouldLog(level)) return;
// In production MCP servers, only log errors to avoid interfering with protocol communication
// In development, allow all logs if DEBUG_MCP is set
const isDebugMode = process.env.DEBUG_MCP === 'true';
if (level === LogLevel.ERROR || isDebugMode) {
const entry: LogEntry = {
timestamp: new Date().toISOString(),
level,
message,
...(data && { data })
};
console.error(JSON.stringify(entry));
}
}
error(message: string, data?: any): void {
this.log(LogLevel.ERROR, message, data);
}
warn(message: string, data?: any): void {
this.log(LogLevel.WARN, message, data);
}
info(message: string, data?: any): void {
this.log(LogLevel.INFO, message, data);
}
debug(message: string, data?: any): void {
this.log(LogLevel.DEBUG, message, data);
}
}
export const logger = new Logger(
process.env.LOG_LEVEL as LogLevel || LogLevel.INFO
);
