Claude Code v2.1.91 Released - MCP Tool Result Persistence and Improved Edit Tool

Anthropic released Claude Code v2.1.91 on April 2, 2026. This update brings several significant improvements including MCP tool result persistence, enhanced shell execution controls, and more efficient editing capabilities.

Key Changes

MCP Tool Result Persistence Override

Developers can now override the default result size limit for MCP tool outputs using the _meta["anthropic/maxResultSizeChars"] annotation, allowing results up to 500K characters to pass through without truncation. This is particularly useful for large database schemas and extensive API responses.

disableSkillShellExecution Setting

A new setting disableSkillShellExecution has been added to disable inline shell execution in skills, custom slash commands, and plugin commands. This provides better security control for teams that want to limit shell command execution from external sources.

Multi-line Prompt Support in Deep Links

The claude-cli://open?q= deep links now support multi-line prompts. Previously, encoded newlines (%0A) were rejected, but this limitation has been removed, enabling more complex query formulations.

Plugin Executables Support

Plugins can now ship executables under the bin/ directory and invoke them as bare commands from the Bash tool, expanding plugin capabilities and integration options.

Edit Tool Optimization

The Edit tool now uses shorter old_string anchors, reducing output tokens and improving overall efficiency when making code modifications.

Performance Improvements

• Faster stripAnsi on Bun through Bun.stripANSI routing
• Eliminated per-turn JSON.stringify of MCP tool schemas on cache-key lookup

Bug Fixes

• Fixed transcript chain breaks on --resume that could lose conversation history
• Fixed cmd+delete behavior on iTerm2, kitty, WezTerm, Ghostty, and Windows Terminal
• Fixed plan mode in remote sessions losing track of the plan file after container restart
• Fixed JSON schema validation for permissions.defaultMode: "auto" in settings.json
• Fixed Windows version cleanup not protecting the active version’s rollback copy
• Improved /feedback to explain why it’s unavailable instead of disappearing

Community Context

The v2.1.88 release incident (where .map files were accidentally included in the npm package) prompted discussions about release verification processes. The community has been monitoring Anthropic’s response to these transparency concerns, and the v2.1.91 release appears to proceed without similar issues.