Stitch MCP integration from Claude.ai fails in Claude Code with auth error

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

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What's Wrong?

Stitch MCP integration from Claude.ai fails in Claude Code with an authentication error, making it impossible to use any Stitch tools.

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What Should Happen?

Expected behavior:
Stitch MCP tools (e.g. list_projects, get_project, generate_screen_from_text) should authenticate and work in Claude Code the same way they do in Claude.ai.

Actual behavior:
Every call to any Stitch MCP tool returns:

Incompatible auth server: does not support dynamic client registration

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Environment

• Claude Code CLI (not VS Code extension)
• macOS
• Stitch MCP loaded via Claude.ai built-in integrations

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Workaround

None found. The tool is listed as available but always fails at authentication.

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Error Messages/Logs

Incompatible auth server: does not support dynamic client registration

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Steps to Reproduce

1. Connect the Stitch integration via Claude.ai
2. Open Claude Code CLI
3. Ask Claude to call any Stitch tool (e.g. "Show me my Stitch projects")
4. Observe: every call fails with the above error regardless of retries

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Additional Context

The Stitch MCP server appears to use an OAuth flow that Claude Code does not support (dynamic client registration). The integration works on Claude.ai but is non-functional in the CLI. Configuring Stitch as a local MCP server in ~/.claude/settings.json may be the only workaround, but no public documentation exists for this.