Fast MCP Server Initializes Twice #301
Description
Describe the bug
When running Fast MCP Server with the current configuration, the server initializes twice in quick succession (within ~1 second). This can be observed in the logs where the "Initializing server..." message appears twice, followed by two successful connections and identical initialize method calls.
To Reproduce
- Configure Fast MCP Server with the following settings:
"git": {
"command": "uv",
"args": [
"run",
"--with",
"mcp[cli]",
"mcp",
"run",
"fastmcp_git_servers.py"
]
}- Start the Claude Desktop app
- Observe the duplicate initialization messages
Observation
The server initializes twice as shown in the logs below. Note the timestamps showing two initialization sequences less than 1 second apart:
2025-03-16T13:52:00.467Z [Git] [info] Initializing server...
2025-03-16T13:52:00.491Z [Git] [info] Server started and connected successfully
2025-03-16T13:52:00.495Z [Git] [info] Message from client: {"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"claude-ai","version":"0.1.0"}},"jsonrpc":"2.0","id":0}
2025-03-16T13:52:01.398Z [Git] [info] Initializing server...
2025-03-16T13:52:01.707Z [Git] [info] Server started and connected successfully
2025-03-16T13:52:01.708Z [Git] [info] Message from client: {"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"claude-ai","version":"0.1.0"}},"jsonrpc":"2.0","id":0}
Expected behavior
The server should initialize only once per execution.
Desktop (please complete the following information):
- OS: macOS Sonoma 14.2.1
- Claude Desktop: 0.8.1
- Python SDK: 1.4.0
Additional context
The non-fast MCP server implementation doesn't have this problem. The key difference appears to be in how the server is launched:
"git": {
"command": "uv",
"args": [
"--directory",
"src/non-fast-mcp-server",
"run",
"git"
]
}