MCP Server Communication Failure on Windows with Antigravity/Gemini Code Assist

Bug Report: MCP Server Communication Failure

Summary

The MCP server @modelcontextprotocol/server-memory starts correctly but Antigravity fails to communicate with it, causing indefinite loading states when calling MCP tools like mcp_conversations_read_graph.

Environment

• OS: Windows
• Extension: Antigravity (Gemini Code Assist)
• MCP Config Location: C:\Users\julio\.gemini\antigravity\mcp_config.json

Configuration

{
    "mcpServers": {
        "conversations": {
            "command": "npx",
            "args": ["-y", "@modelcontextprotocol/server-memory"],
            "env": {
                "MEMORY_FILE_PATH": "C:\\Users\\julio\\.gemini\\antigravity\\mcp_memory.json"
            }
        }
    }
}

Steps to Reproduce

1. Configure MCP server as shown above
2. Start/reload VSCode with Antigravity
3. Attempt to use any MCP tool (e.g., mcp_conversations_read_graph)
4. Result: Tool hangs indefinitely with "Loading..." state, never returns

Diagnosis Performed

1. Server Runs Correctly Manually

MEMORY_FILE_PATH="C:/Users/julio/.gemini/antigravity/mcp_memory.json" npx -y @modelcontextprotocol/server-memory
# Output: "Knowledge Graph MCP Server running on stdio"

2. Node Processes Are Running

node.exe  PID 11404
node.exe  PID 3260

3. Memory File Never Created

The mcp_memory.json file is never created, indicating the server is never successfully invoked by Antigravity.

Expected Behavior

MCP tools should return results within seconds, not hang indefinitely.

Actual Behavior

MCP tools hang indefinitely. User must manually cancel the operation.

Suspected Cause

The stdio communication channel between Antigravity and the MCP server is not being established correctly on Windows.

No repository file or failing test is named. Start by reproducing the Windows setup from the Antigravity mcp_config.json and the manual npx command, then trace whether the stdio connection is established; done means MCP tools return results within seconds and mcp_memory.json is created.