Claude Code 2.1.299 fixes MCP server name collision in permission rules

Claude Code 2.1.299, released October 14, 2026, fixes a bug where an allow rule mcp__a also matched a server named a__b, since server names may contain double underscores. Allow rules now reach only the named server, and deny and ask rules correctly apply to names with double underscores.

• Claude Code 2.1.299 shipped October 14, 2026 with 131 bug fixes
• Rule mcp__a no longer covers servers a__b and a_
• MCP server names may contain double underscores, breaking name parsing
• Deny and ask rules now apply to names with double underscores