canimcp reveals which MCP clients silently break your server's tools

A developer released canimcp, a tool that takes a saved tools/list response or a server command and reports which client versions break on specific MCP schemas. It was prompted by a tool with a root oneOf that stayed invisible to Claude Code for 17 days with no errors on either side.

• canimcp runs via npx with zero dependencies on Node 18+
• Claude Code silently drops a tool with an ids[] argument
• Codex compacts a 14 KB schema and loses required nested fields
• On a server with 2049 tools, Codex keeps only the first 2048