Feature Request: Log File Size Management and Rotation

Is your feature request related to a problem?

Yes. The @modelcontextprotocol/server-filesystem MCP server generates unbounded log files in %APPDATA%\Claude\logs\mcp-server-filesystem*.log (Windows) / ~/Library/Logs/Claude/ (macOS) that can grow to excessive sizes (17+ MB observed), creating several issues:

1. Performance degradation: Large log files slow down log viewing and parsing during troubleshooting
2. Disk space waste: Logs consume unnecessary space without automatic cleanup
3. Troubleshooting obstruction: Ironically, oversized logs defeat their debugging purpose by becoming unwieldy
4. User maintenance burden: Manual cleanup required, which most users won't perform regularly

Describe the solution you'd like

Add configurable log rotation with size-based and/or time-based triggers:

Proposed Configuration Options

Environment Variables:

MCP_FILESYSTEM_LOG_MAX_SIZE=10485760  # Max log size in bytes (default: 10MB)
MCP_FILESYSTEM_LOG_MAX_FILES=5        # Number of rotated logs to retain (default: 5)
MCP_FILESYSTEM_LOG_ROTATION=size      # Rotation strategy: 'size', 'time', or 'both' (default: size)
MCP_FILESYSTEM_LOG_INTERVAL=86400     # Rotation interval in seconds (default: daily)

Alternative: Command-line Arguments:

npx @modelcontextprotocol/server-filesystem \
  --log-max-size 10M \
  --log-max-files 5 \
  --log-rotation size \
  /path/to/allowed/dir

Rotation Behavior

1. Size-based rotation: When log file exceeds LOG_MAX_SIZE, rotate immediately
2. Time-based rotation: Rotate at fixed intervals (e.g., daily at midnight)
3. File naming convention: mcp-server-filesystem.log, mcp-server-filesystem.log.1, mcp-server-filesystem.log.2, etc.
4. Automatic cleanup: Delete oldest log when LOG_MAX_FILES limit reached
5. Graceful degradation: If rotation fails, log to stderr and continue operation

Describe alternatives you've considered

1. External log rotation tools:

   • Windows Task Scheduler + batch scripts
   • Linux logrotate
   • Problem: Requires per-user configuration; not portable across installations

2. Desktop Commander MCP: Includes 10MB auto-rotation but introduces complexity for users only needing basic filesystem access

3. Manual periodic deletion: Impractical; most users unaware logs exist until problems arise

Additional context

• Related discussion: Issue #1879 proposes environment variable configuration; log management would complement that effort
• Community need: Multiple users report log bloat issues in Discord/support channels
• Reference implementation: Desktop Commander MCP successfully implements 10MB rotation

Implementation Notes

Consider using established Node.js logging libraries with built-in rotation:

• winston with winston-daily-rotate-file
• pino with pino-roll
• Or lightweight custom implementation (~50 LOC)

Default to conservative settings (10MB max, 5 file retention) to balance disk usage against debugging needs.

Would you be willing to submit a PR?

Potentially, depending on maintainer guidance regarding preferred implementation approach (library vs. custom, env vars vs. CLI args).

Start by locating the @modelcontextprotocol/server-filesystem logging entry point and checking how its Windows and macOS log paths are configured. Compare the proposed environment-variable and command-line options, then define rotation behavior, retention limits, failure handling, and tests that demonstrate bounded log files.