Add opt-out flag for auto-synced claude.ai connector MCP servers

Summary

Claude Code automatically registers every connector available on the user's claude.ai account as an MCP server, regardless of whether the user has connected it. There is no local way to opt out, so each session pays context overhead for connectors the user never uses.

Current behavior

claude mcp list shows the synced connectors (truncated example):

claude.ai LegalZoom: https://www.legalzoom.com/mcp/claude/v1 - ! Needs authentication
claude.ai ZoomInfo: https://mcp.zoominfo.com/mcp - ! Needs authentication
claude.ai Adobe for creativity: https://adobe-creativity.adobe.io/mcp - ! Needs authentication
claude.ai monday.com: https://mcp.monday.com/mcp - ! Needs authentication
... (15 more)

Each contributes a deferred authenticate / complete_authentication tool pair (~250–330 tokens). With 15+ connectors that's ~9k tokens of context overhead per session, paid even when none of the connectors are ever invoked.

What does not work

• claude mcp remove \"claude.ai LegalZoom\" → No MCP server found with name: \"claude.ai LegalZoom\". Configured servers: atlassian (the synced entries are not in user/project/local scope)
• Disconnecting the connector on claude.ai → only changes auth state; the entry still appears in claude mcp list
• Deleting ~/.claude/mcp-needs-auth-cache.json → regenerates on the next claude mcp list call with identical mcpsrv_* IDs (the cache is a downstream memo of \"these need auth\", not the source of registration)
• Editing ~/.claude.json → no claude.ai * entries exist in the file; the registry is synthesized at runtime from the user's oauthAccount

Proposed

A user-level setting (or env var / CLI flag) such as:

{ \"disableClaudeAiMcpSync\": true }

that suppresses auto-registration of the claude.ai-account connectors. Users who only need one or two connectors (often added explicitly as a custom MCP entry) would no longer pay overhead for the rest.

Why

The per-connector cost is small individually, but the synced list grows with every connector Anthropic adds to the directory, and there's no way for end users to push back on it locally. This particularly affects users on enterprise orgs where the available-connector list is set by the admin and cannot be pruned by the user.

Version

Claude Code 2.1.131