mcp-use/dist/src/logging.js

A utility library for integrating Model Context Protocol (MCP) with LangChain, Zod, and related tools. Provides helpers for schema conversion, event streaming, and SDK usage.

import fs from 'node:fs';
import path from 'node:path';
import { createLogger, format, transports } from 'winston';
const { combine, timestamp, label, printf } = format;
let MCP_USE_DEBUG = 0;
const debugEnv = process.env.DEBUG?.toLowerCase();
if (debugEnv === '2') {
    MCP_USE_DEBUG = 2;
}
else if (debugEnv === '1') {
    MCP_USE_DEBUG = 1;
}
const defaultFormat = printf(({ level, message, label, timestamp }) => `${timestamp} [${label}] ${level.toUpperCase()}: ${message}`);
export class Logger {
    static loggers = {};
    static getLogger(name = 'mcp_use') {
        if (!this.loggers[name]) {
            this.loggers[name] = createLogger({
                level: 'warn',
                format: combine(label({ label: name }), timestamp(), defaultFormat),
                transports: [],
            });
        }
        return this.loggers[name];
    }
    static configure(level, toConsole = true, toFile) {
        const root = this.getLogger();
        if (!level) {
            level
                = MCP_USE_DEBUG === 2
                    ? 'debug'
                    : MCP_USE_DEBUG === 1 ? 'info' : 'warn';
        }
        root.level = level;
        root.clear();
        if (toConsole) {
            root.add(new transports.Console());
        }
        if (toFile) {
            const dir = path.dirname(toFile);
            if (dir && !fs.existsSync(dir)) {
                fs.mkdirSync(dir, { recursive: true });
            }
            root.add(new transports.File({ filename: toFile }));
        }
    }
    static setDebug(debugLevel = 2) {
        MCP_USE_DEBUG = debugLevel;
        process.env.LANGCHAIN_VERBOSE = debugLevel >= 1 ? 'true' : 'false';
        const newLevel = debugLevel === 2
            ? 'debug'
            : debugLevel === 1 ? 'info' : 'warn';
        Object.values(this.loggers).forEach((log) => {
            log.level = newLevel;
        });
    }
}
Logger.configure();
export const logger = Logger.getLogger();