MCP tool text output not displayed to user in terminal

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

MCP tool results are not displayed to the user in the Claude Code terminal. The assistant receives the results and can summarize them, but the user sees only the tool call label with no output rendered.

This affects an MCP server that returns only TextContent (no structuredContent). The server is registered as a user-scoped MCP server via claude mcp add --scope user.

Key Details

• The MCP server returns standard TextContent responses — no structuredContent field at all
• The assistant does receive the full tool result and can reference/summarize it
• The user sees nothing — just the tool call indicator with no output
• This used to work in earlier versions of Claude Code
• Tested with both plugin-provided MCP servers and user-scoped MCP servers — same behavior

Difference from #9962

Issue #9962 was about structuredContent being prioritized over TextContent (JSON-wrapped display). This is different:

• Our server returns only TextContent (no structuredContent)
• The result is not displayed in the wrong format — it's not displayed at all

Steps to Reproduce

1. Create an MCP server that returns only TextContent results (no structuredContent)
2. Register it via claude mcp add --scope user
3. Call any tool on that server
4. Observe: assistant receives the result, but user sees no output in the terminal

What Should Happen?

The TextContent from MCP tool results should be displayed to the user in the terminal, as it was in earlier versions.

Claude Model

Claude Opus 4.6

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Unknown — it worked as recently as a few weeks ago

Claude Code Version

2.1.96

Platform

Anthropic API (also tested with Claude Max)

Operating System

macOS (Darwin 25.3.0)

Terminal/Shell

zsh, iTerm2 / VS Code terminal