claude_design MCP server fails with 404 on /v1/design/mcp despite successful auth

[AnewarFlutter]

Description

The claude_design MCP server fails to connect with an HTTP 404 error, even after successfully running /design-login (which reports "Design-system access authorized").

Steps to reproduce

1. Run /design-login → returns "Design-system access authorized."
2. Run /mcp to reconnect → fails with:

   Failed to reconnect to claude_design: HTTP 404 at https://api.anthropic.com/v1/design/mcp
   

3. claude_design tools (e.g. mcp__claude_design__get_claude_design_prompt) remain unavailable in the session.

Expected behavior

After successful authentication via /design-login, the claude_design MCP server should connect successfully and expose its tools.

Actual behavior

The MCP server consistently returns 404 at https://api.anthropic.com/v1/design/mcp, even though:

• claude.ai/design is accessible and working normally in the browser.
• /design-login reports successful authorization.

Environment

• Claude Code CLI
• Platform: macOS (Darwin 25.5.0)

[github-actions]

Found 2 possible duplicate issues:

1. MCP server 'claude_design' (frontend-design plugin): 404 Streamable HTTP error #69307
2. [BUG] claude_design MCP server injected dynamically but endpoint returns 404 #69309

This issue will be automatically closed as a duplicate in 3 days.

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[github-actions]

This issue has been automatically closed as a duplicate of #69307.

If this is incorrect, please re-open this issue or create a new one.

🤖 Generated with Claude Code