MCP tool calls display generic 'Called <server>' instead of tool name and params since ~2.1.105

Description

Since approximately v2.1.105, MCP tool calls in the terminal UI display a generic collapsed format instead of the rich format that was shown previously.

Before (~2.1.104):

plugin:server - toolname (MCP)(param: "value")

After (2.1.105+):

Called plugin:server

The rich format showed the specific tool function name, the (MCP) type label, and inline parameter values — all useful context for MCP tools where the server namespace alone doesn't tell you what was called. The new collapsed format loses all of this.

Root Cause

This appears to be driven by the tengu_sotto_voce and tengu_swann_brevity: "focused" GrowthBook feature flags, which were rolled out server-side and activate a quieter rendering mode in 2.1.105+. The userFacingName() in client.ts still generates the full ${client.name} - ${displayName} (MCP) string, but the sotto voce rendering path overrides it with the generic format.

Why This Matters for MCP Tools

The collapsed format makes sense for built-in tools (Read, Edit, Grep) where the tool name is self-evident from context. But for MCP/plugin tools:

• A server may expose 10+ tools — knowing which tool was called matters (e.g., send vs reply vs history on a messaging server)
• Parameter values provide immediate feedback (e.g., seeing who a message was sent to)
• Without this, users must expand every tool call or enable full verbose mode to understand what happened

Reproduction

1. Install any MCP server with multiple tools (e.g., a messaging plugin, database plugin)
2. Run Claude Code 2.1.105+
3. Call any MCP tool
4. Observe Called <server-name> instead of <server-name> - <tool> (MCP)(<params>)

Compare with the same setup on 2.1.104 or earlier — the rich format is shown.

Suggested Fix

Either:

• Exclude MCP tools from sotto voce / brevity rendering (always show userFacingName + params for MCP tools)
• Add a user-facing setting to opt out of sotto voce mode (the GrowthBook override CLAUDE_INTERNAL_FC_OVERRIDES is ant-internal only and stripped from the public build)
• Show at minimum the tool function name (not just the server namespace) in the collapsed format

Environment

• macOS (Darwin 25.1.0)
• Claude Code 2.1.107
• Multiple MCP plugin servers configured