Feature Request: Allow MCP servers to be disabled by default (lazy loading)

Problem

Currently, all configured MCP servers auto-start when Claude Code launches. There's no way to have MCP servers "available but not running" - they're either configured (and auto-start) or not configured at all.

When you have multiple MCP servers configured (e.g., playwright, jupyter, greptile, supabase), startup becomes slower and resources are consumed even when those servers aren't needed for the current session.

Proposed Solution

Add an optional autoStart (or enabled / lazy) property to MCP server configurations:

{
  "mcpServers": {
    "playwright": {
      "command": "npx",
      "args": ["@anthropic/playwright-mcp"],
      "autoStart": false
    }
  }
}

When autoStart: false:

• The server config is preserved but the server doesn't launch at startup
• User can enable it mid-session via a command like /mcp enable playwright
• Or Claude could auto-start it when a tool from that server is first requested

Benefits

• Faster startup times
• Lower resource usage for servers not needed in current session
• Users can keep many MCP servers configured without performance penalty
• Better developer experience for users with diverse tooling needs

Current Workaround

The only workaround is to claude mcp remove servers and claude mcp add them back when needed, which is tedious and loses configuration.