Plugin MCP server not registered/searchable in current session despite `claude mcp list` showing "Connected"

Environment

• Claude Code version: 2.1.220
• macOS: 26.5.2 (build 25F84)
• Plugin: legal-it@mcp-legal-it v2.10.1 (marketplace: capazme/mcp-legal-it), enabled via project .claude/settings.json (enabledPlugins)

Steps to reproduce

1. Plugin already installed at user scope but disabled there; enabled via project-level .claude/settings.json
2. Open Claude Code session in that project
3. claude mcp list shows the plugin's MCP server as "✔ Connected" (plugin:legal-it:legal-it)
4. Ask Claude to list/use tools from that server, or search for them via ToolSearch / deferred-tool list
5. No tools from the plugin appear — not in the deferred-tools system reminder, not via ToolSearch, not via ListMcpResourcesTool (only the standard claude.ai-connected MCP servers show up)

Expected

If claude mcp list reports the server as Connected, its tools should be indexed and callable/searchable in that same session.

Actual

Server shows Connected at the CLI level but the session's tool registry never picks up its tools. Reproduced across multiple fresh session restarts (new tabs, claude relaunched) in the same project — not resolved by simply closing/reopening.

Notes

• Ruled out slow first-run bootstrap: the plugin's MCP server uses uv run which on first launch downloads Python 3.12 + deps (~20-30s). Manually invoking start_server.sh outside the session confirms the server responds correctly to the MCP initialize handshake in ~0.66s once the uv/venv cache is warm — so slow startup was a contributing factor on the very first attempt, but does not explain later restarts still failing to surface tools.
• claude plugin list confirms: legal-it@mcp-legal-it, scope: user, disabled in ~/.claude/settings.json but enabled by project settings (tool correctly reports this override).