SSE MCP Server works perfectly but Claude Web Interface won't connect - Need help with browser extension workaround

[JanyaBayana]

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Question Category

• Protocol Specification
• SDK Usage
• Server Implementation
• General Implementation
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Your Question

Background:
I've built a MCP server using Python Flask that exposes some data through MCP tools. The server implements SSE (Server-Sent Events) transport and is fully functional - all the JSON-RPC protocols are working correctly, authentication passes, and tools are properly listed.

Technical Details:
Server: Python Flask with SSE endpoint at /{token}/sse
Transport: HTTP with Server-Sent Events (SSE)
Protocol: MCP 2024-11-05 compliant
Authentication: Token-based with Firestore backend
Tools: account listing, property querying, quota management

The Problem:
My logs show everything working perfectly:
-> Successful MCP handshake (initialize method)
-> Proper tool listing (tools/list returns correct schema)
-> Authentication working (user resolved from token)
-> JSON-RPC 2.0 compliant responses

But Claude's web interface simply won't connect.

What I'm Looking For:

1. Has anyone successfully used the claude-mcp browser extension mentioned in the codemcp project to connect SSE MCP servers to Claude's web interface?
2. Are there other community workarounds for connecting web Claude to remote MCP servers?

Any guidance would be greatly appreciated!