Issue Station
Sign In
Tools hereToolbox

claude-code - 💡(How to fix) Fix Custom MCP Connectors return 403/Not connected in Claude Code mode but work in Claude chat mode

Official PRs (…)
ON THIS PAGE

Recommended Tools

×6

Utilities matched from this issue’s tags and category — try them while you read without losing context.

GitHub issue graph ai analysis

Paste a GitHub issue URL. We fetch that issue, discover linked issues from bodies/comments/timeline, collect linked pull requests, and produce a structured English report.

The report is written in English Markdown for sharing and archival.

Helpful · Quick feedback

Loading…

Custom MCP Connectors configured in Claude Desktop (Settings → Connectors) are not functional when called from Claude Code mode (the embedded CLI in Claude Desktop). The same connectors work fine in regular Claude chat mode.

Root Cause

Custom MCP Connectors configured in Claude Desktop (Settings → Connectors) are not functional when called from Claude Code mode (the embedded CLI in Claude Desktop). The same connectors work fine in regular Claude chat mode.

Code Example

GET https://kb.mofanai.cloud/.well-known/oauth-authorization-server
→ { "issuer": "https://kb.mofanai.cloud/", ... }  ✓
RAW_BUFFERClick to expand / collapse

Summary

Custom MCP Connectors configured in Claude Desktop (Settings → Connectors) are not functional when called from Claude Code mode (the embedded CLI in Claude Desktop). The same connectors work fine in regular Claude chat mode.

Environment

  • Claude Desktop (Windows 11)
  • Claude Code embedded in Claude Desktop
  • Two custom MCP connectors configured: https://kb.mofanai.cloud/mcp (jason-kb) and https://game-kb.mofanai.cloud/mcp (game-kb)
  • Both connectors use OAuth + Streamable HTTP transport (Python MCP SDK)

Behavior

  • Claude chat mode: Connectors work as expected
  • Claude Code mode: All tool calls return 403 or Not connected regardless of connector auth state

What I've verified

  • MCP server access logs (Caddy + Python MCP SDK): zero requests received when tool calls are made from Claude Code — the 403 originates in Anthropic's connector proxy layer, not from the server
  • OAuth flow completes successfully (browser popup appears, token issued, connector shows "Connected" in UI)
  • Server-side OAuth state is intact: valid access tokens present, correct issuer/resource metadata
  • Anthropic support confirmed: "This appears to be an auth state synchronization issue on our side. The 403 errors happening without requests reaching your server indicate the problem is in our connector proxy layer."
  • Tried: Disconnect → wait 3 min → reconnect via incognito → clear cookies → new conversation. Issue persists.
  • Both connectors stopped working in Claude Code mode. Other MCP tools (non-Connector) work fine.

Expected behavior

Custom Connectors configured in Claude Desktop should be callable from Claude Code mode, same as from chat mode.

Additional context

The connectors are accessible externally and OAuth metadata is correct:

GET https://kb.mofanai.cloud/.well-known/oauth-authorization-server
→ { "issuer": "https://kb.mofanai.cloud/", ... }  ✓

Anthropic support has been contacted and a manual token reset was attempted but did not resolve the issue, suggesting this may be a broader bug affecting Claude Code's access to Connector-based MCP servers.

Vote matrix · Quick signals

Works
Did the solution work? Tap to confirm.
Easy Fix
Was it a quick fix?
Time Saver
Did it save you time?
Blocking
Was it severely blocking?
Common Issue
Are others likely hitting this too?
Flaky / Intermittent
Is it intermittent?
Verified / Reproducible
Can you reproduce it reliably?
Loading…

FAQ

Expected behavior

Custom Connectors configured in Claude Desktop should be callable from Claude Code mode, same as from chat mode.

#GPU compatibility#latency issue#model loading#dependency error#configuration error

Still need to ship something?

×6

Another batch ranked right after the header list — different links, same matching logic.

Back to top recommendations

TRENDING

claude-code - 💡(How to fix) Fix Custom MCP Connectors return 403/Not connected in Claude Code mode but work in Claude chat mode