Claude Code v2.1.121 Release Notes

Claude Code v2.1.121 brings enhanced MCP server controls, improved plugin management, and significant memory leak fixes for power users.

April 28, 2026 • 10 min read • By ClaudeWorld

Claude Code v2.1.121 is here with a robust set of improvements focused on enhancing developer productivity and system reliability. This release introduces powerful new MCP server configuration options, streamlined plugin management, and critical memory optimizations that will make your Claude Code experience smoother and more efficient.

What’s New

MCP Server Enhancements

Always-Load Tool Configuration: MCP servers now support an alwaysLoad option in their configuration. When set to true, all tools from that server bypass tool-search deferral and remain constantly available, perfect for frequently-used development tools.

Improved Error Handling: MCP servers that encounter transient startup errors now automatically retry up to 3 times instead of remaining disconnected, significantly improving reliability.

Enhanced Authentication: The SDK’s mcp_authenticate function now supports redirectUri for custom scheme completion and claude.ai connectors.

Plugin Management Improvements

Plugin Cleanup: The new claude plugin prune command removes orphaned auto-installed plugin dependencies, helping keep your environment clean. Additionally, plugin uninstall --prune now cascades removals automatically.

Streamlined Skills Navigation: The /skills command now includes a type-to-filter search box, making it easy to find specific skills in long lists without endless scrolling.

User Experience Enhancements

Fullscreen Mode Improvements:

  • Typing in the prompt no longer automatically jumps scroll position back to bottom after scrolling up to read earlier output
  • Clicking any line of a wrapped URL now opens the complete URL
  • Better dialog scrolling with arrow keys, PgUp/PgDn, home/end, and mouse wheel support

Terminal Integration: The /terminal-setup command now automatically enables iTerm2’s clipboard access setting, ensuring /copy works seamlessly, even from tmux sessions.

Enhanced Tool Hooks: PostToolUse hooks can now replace tool output for all tools via hookSpecificOutput.updatedToolOutput (previously limited to MCP-only).

Performance and Reliability

Critical Memory Fixes:

  • Resolved unbounded memory growth when processing many images in sessions
  • Fixed /usage command memory leaks on machines with large transcript histories
  • Addressed memory leaks in long-running tools that fail to emit clear progress events

Improved Stability:

  • Fixed Bash tool becoming unusable when the startup directory is deleted mid-session
  • Enhanced --resume functionality with better error handling and corruption recovery
  • Faster startup times after upgrades

Platform-Specific Improvements

VSCode Integration:

  • Voice dictation now respects accessibility.voice.speechLanguage settings
  • /context command opens a native token usage dialog

Cloud Platform Support: Added Vertex AI support for X.509 certificate-based Workload Identity Federation (mTLS ADC).

Enhanced Monitoring: OpenTelemetry spans now include stop_reason, gen_ai.response.finish_reasons, and optional user_system_prompt logging.

How to Update

To upgrade to Claude Code v2.1.121:

  1. Check your current version: Run claude --version
  2. Update via your package manager or download from the official release page
  3. Restart any active sessions to ensure all new features are available
  4. Review your MCP server configurations to take advantage of the new alwaysLoad option
  5. Run claude plugin prune to clean up any orphaned dependencies