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MCP remote server response parsing fails with "data couldn't be read" error (macOS Apple Silicon) #8298

@swing62

Description

@swing62
  • Jan version: 0.8.2
  • OS: macOS, Apple Silicon (M4, 16GB RAM)
  • Model: Qwen2.5-7B-Instruct-4bit (MLX)

When using Exa MCP server via mcp-remote (STDIO → HTTP bridge),
the tool is called correctly ("Used Web Search Exa" appears in UI)
but Jan fails to parse the response with error:
"The data couldn't be read because it isn't in the correct format."

Separately, all STDIO-native MCP servers (SearXNG-MCP, Fetch)
fail at handshake with EPIPE error:
"Error: write EPIPE" in node:internal/stream_base_commons

The STDIO server itself works correctly when tested manually:
echo '{"jsonrpc":"2.0","method":"initialize",...}' | npx -y searxng-mcp
→ returns valid JSON response

So the bug is in Jan's pipe handling, not in the MCP servers.

{
"Exa": {
"active": true,
"command": "/usr/local/bin/npx",
"args": ["-y", "mcp-remote", "https://mcp.exa.ai/mcp?exaApiKey=***"]
}
}

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