/**
* stderr-only logger for MCP server.
* stdout is reserved for the MCP protocol (stdio transport).
*/
let debugEnabled = false;
/**
* Enable or disable debug logging.
*/
export function setDebug(enabled: boolean): void {
debugEnabled = enabled;
}
/**
* Check if debug logging is enabled.
*/
export function isDebugEnabled(): boolean {
return debugEnabled;
}
/**
* Log a debug message to stderr (only if debug is enabled).
*/
export function debug(message: string, data?: unknown): void {
if (!debugEnabled) return;
const timestamp = new Date().toISOString();
if (data !== undefined) {
console.error(`[${timestamp}] [DEBUG] ${message}`, JSON.stringify(data));
} else {
console.error(`[${timestamp}] [DEBUG] ${message}`);
}
}
/**
* Log an info message to stderr.
*/
export function info(message: string): void {
const timestamp = new Date().toISOString();
console.error(`[${timestamp}] [INFO] ${message}`);
}
/**
* Log a warning message to stderr.
*/
export function warn(message: string, err?: unknown): void {
const timestamp = new Date().toISOString();
if (err instanceof Error) {
console.error(`[${timestamp}] [WARN] ${message}: ${err.message}`);
} else if (err !== undefined) {
console.error(`[${timestamp}] [WARN] ${message}:`, err);
} else {
console.error(`[${timestamp}] [WARN] ${message}`);
}
}
/**
* Log an error message to stderr.
*/
export function error(message: string, err?: unknown): void {
const timestamp = new Date().toISOString();
if (err instanceof Error) {
console.error(`[${timestamp}] [ERROR] ${message}: ${err.message}`);
if (debugEnabled && err.stack) {
console.error(err.stack);
}
} else if (err !== undefined) {
console.error(`[${timestamp}] [ERROR] ${message}:`, err);
} else {
console.error(`[${timestamp}] [ERROR] ${message}`);
}
}
export const log = { debug, info, warn, error, setDebug, isDebugEnabled };
