VSCode extension: Plugin MCP tools not indexed in deferred tool search, causing misrouted tool calls

Description

Plugin MCP tools (specifically mcp__plugin_slack_slack__* from slack@claude-plugins-official) are functional and callable in the VSCode extension, but they do not appear in the deferred tool search index. This causes Claude to route requests to the wrong tool.

Steps to Reproduce

1. Install the official Slack plugin (slack@claude-plugins-official) — confirmed enabled in settings.json
2. Open Claude Code in the VSCode extension
3. Ask Claude to search or read Slack
4. Observe that Claude uses mcp__claude_ai_Notion__notion-search (which lists Slack as a "connected source") instead of the actual mcp__plugin_slack_slack__* tools

Evidence

• Calling mcp__plugin_slack_slack__slack_read_user_profile directly works and returns correct data
• But ToolSearch for "slack" or "+plugin_slack" returns zero plugin Slack tools — only mcp__claude_ai_Notion__notion-search (because its description mentions Slack as a connected source)
• The mcp__plugin_slack_slack__* tools are completely absent from the deferred tools list

Expected Behavior

Plugin MCP tools should be indexed in the deferred tool search so Claude can discover and use them when relevant. At minimum, mcp__plugin_slack_slack__* should appear when searching for "slack".

Actual Behavior

Plugin MCP tools are loaded and callable but invisible to tool search, causing Claude to consistently misroute Slack requests through Notion's connected source search instead.

Environment

• Claude Code VSCode extension
• macOS (Darwin 25.3.0)
• Slack plugin version: 1.0.0 (installed 2026-03-12)
• Plugin is enabled in settings.json under enabledPlugins

Workaround

None.