You'll noticeTier: how much it should matter to you
1Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
MCPArea: what it touches
ImprovementsKind: in v2.1.295,
ImprovementsSection of the release
What
MCP tools (outside tools connected to Claude Code) return results that can include extra fields: _meta for details and structuredContent for data in a fixed shape. Size limits on these have changed:
_meta that is too large is now dropped. Before, only structuredContent had a limit.
Tools that list a ui:// resource, an interface they provide, get a higher limit.
If a hook (a script you set to run around tool calls) replaces a tool's output with one that has too many fields, the output is cut down to text, inline images and inline PDFs, with a note saying parts were left out.
Tools that list _meta.ui are no longer exempt from the structuredContent limit.
Why
Large results from MCP tools can now lose their _meta details. If you build MCP tools that rely on that field, keep it small.
