`list_tools` returns empty when connecting to MetaMCP via mcp-proxy (SSE)

[mehmetbaykar]

Description

I am running a self-hosted instance of MetaMCP which aggregates approximately 10 different MCP servers. I am attempting to connect Code Mode to this MetaMCP instance to give the agent access to all aggregated tools at once.

I followed the official setup guide and the YouTube tutorial, configuring my .utcp_config.json to use the mcp call template with uvx mcp-proxy.

Current Behavior
The connection appears to initialize without crashing, but when the LLM (or manual execution) calls list_tools or search_tools, the result is always empty. No tools from the MetaMCP instance are discovered or registered by Code Mode.

Configuration
Here is the .utcp_config.json configuration I am using:

{
  "manual_call_templates": [
    {
      "name": "metamcp",
      "call_template_type": "mcp",
      "config": {
        "mcpServers": {
          "metamcp": {
            "command": "uvx",
            "args": [
              "mcp-proxy",
              "--transport",
              "streamablehttp",
              "https://metamcp.myserver.com/metamcp/Default/sse"
            ],
            "env": {
              "API_ACCESS_TOKEN": "MYAPIACCESSTOKEN" 
            }
          }
        }
      }
    }
  ]
}

Environment

• OS: [macOS ]
• Transport: SSE (Server-Sent Events)
• Proxy: mcp-proxy via uvx
• Aggregation: MetaMCP hosting ~10 servers

Expected Behavior
Code Mode should connect to the MetaMCP SSE endpoint, perform the handshake, and list_tools should populate with the tools aggregated by MetaMCP (e.g., github, filesystem, etc.), allowing the agent to call them via the metamcp namespace.

Possible Cause / Question
It seems like the authentication or tool discovery handshake is failing silently.

1. Is uvx correctly passing the env variables (specifically API_ACCESS_TOKEN) to the spawned mcp-proxy process?
2. Does Code Mode support tool discovery over an SSE connection bridged by stdio in this specific configuration?

Any guidance on debugging the connection handshake would be appreciated.

[mehmetbaykar]

@h3xxit any idea why this is failing?

[h3xxit]

Most likely some error during MCP registration. I recommend using the mcp inspector and using the same mcp config (to register the code mode mcp server) and see what error pops up there: https://github.com/modelcontextprotocol/inspector

[h3xxit]

MCP SSE is also deprecated, and has been replaced with http, so it might not be properly supported.