You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
MCPArea: what it touches
ImprovementsKind: in v2.1.321,
ImprovementsSection of the release
What
MCP servers are outside programs that give Claude Code extra tools, and each tool describes its inputs in a schema. Some schemas offer several alternative shapes, which Claude Code combines into one. If that combining would take too much memory because the schema uses numeric property names, Claude Code now drops the tool.
Why
If an unusual MCP tool goes missing, this can be why. Claude Code shows a message saying the tool would take too much memory.
