[FEATURE] Show MCP tool name and arguments in VSCode extension chat

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When an MCP tool is called in the Claude Code VSCode extension chat, the UI only shows the server name and method (e.g. Gateway [execute_tool]), with no indication of which specific tool is being invoked or what arguments are passed.

This makes it impossible to follow Claude's reasoning in real time — you can see that a tool was called, but not what it actually did.

<img width="814" height="678" alt="Image" src="https://github.com/user-attachments/assets/93c34cb5-5bb3-47fd-aa7d-26689fbc456c" />

Proposed Solution

The chat should display the actual tool name (e.g. execute_tool → query_db) and ideally a summary of the arguments, similar to what the CLI already shows.

Alternative Solutions

Use the CLI (claude in terminal) which already displays full tool names and arguments — but this defeats the purpose of using the VSCode extension.

Priority

High - Significant impact on productivity

Feature Category

MCP server integration

Use Case Example

While using Claude Code in the VSCode extension, I call a custom MCP gateway that routes to multiple tools (query_db, search_web_pro, validate_code_name, etc.). All tool calls appear as Gateway [execute_tool] — I have no way to know which tool ran, with what arguments, or whether it succeeded without switching to the terminal.

Additional Context

See attached screenshot showing Gateway [execute_tool] with no tool name visible.