Tool Discovery Failure Causing MCP Server Crash in Local Development Environment

Bug Description
In the latest version of Claude Code, MCP servers I have developed locally - that used to work just fine with Claude Code - are now failing to find tools. And whenever this happens, it completely breaks Claude Code (ctrl-C required to terminate the process.)

ReferenceError: Tool not found for mcp__expert__list_topics
at file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:1726:855
at Object.useMemo (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:91:25822)
at M59.useMemo (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:52:18366)
at Rg (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:1726:706)
at fV6 (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:1726:1768)
at sB (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:91:19349)
at N_ (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:93:42517)
at Q6 (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:93:38085)
at ZO (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:93:38013)
at FV (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:93:37867)

ERROR Tool not found for mcp__expert__list_topics
file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:1726:855

• (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:1726:855)
• Object.useMemo (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:91:25822)
• M59.useMemo (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:52:18366)
• Rg (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:1726:706)
• fV6 (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:1726:1768)
• sB (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:91:19349)
• N_ (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:93:42517)
• Q6 (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:93:38085)
• ZO (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:93:38013)
• FV (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:93:37867)

Environment Info

• Platform: macos
• Terminal: vscode
• Version: 0.2.86
• Feedback ID: 126824f5-def8-4027-8914-20fc8023b548

Errors

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