Claude Code v2.1.91 Release Notes

Claude Code v2.1.91 introduces MCP tool result persistence, shell execution controls, multi-line deep links, and important bug fixes for transcript handling and plan mode.

April 3, 2026 • 10 min read • By ClaudeWorld

The Claude Code development team has released version 2.1.91, bringing significant improvements to tool result handling, security controls, and user experience enhancements that power users have been requesting.

What’s New

Enhanced MCP Tool Result Handling

This release introduces a game-changing feature for handling large tool results. You can now override MCP tool result persistence using the _meta["anthropic/maxResultSizeChars"] annotation, supporting up to 500K characters. This is particularly valuable when working with large database schemas or extensive API responses that were previously truncated.

Security and Control Improvements

A new disableSkillShellExecution setting gives you granular control over inline shell execution in skills, custom slash commands, and plugin commands. This addresses security concerns while maintaining flexibility for trusted environments.

Plugins can now ship executables under the bin/ directory and invoke them as bare commands from the Bash tool, streamlining plugin development workflows. Additionally, multi-line prompts are now supported in claude-cli://open?q= deep links, with encoded newlines (%0A) properly handled.

Critical Bug Fixes

Several important stability issues have been resolved:

  • Fixed transcript chain breaks on --resume that could lose conversation history
  • Resolved cmd+delete behavior issues across multiple terminals (iTerm2, kitty, WezTerm, Ghostty, Windows Terminal)
  • Fixed plan mode losing track of plan files after container restarts in remote sessions
  • Corrected JSON schema validation for permissions.defaultMode: "auto"

Performance and UX Improvements

The release includes performance optimizations, particularly faster stripAnsi processing on Bun runtime. The edit tool now uses shorter old_string anchors to reduce output tokens, and the /claude-api skill provides improved guidance for agent design patterns.

How to Update

To update to Claude Code v2.1.91:

  1. Check your current version with claude --version
  2. Update using your package manager or download the latest release
  3. Restart any active Claude Code sessions
  4. Review the new disableSkillShellExecution setting if security is a concern in your environment