I have built my own MCP server using Cursor and it works with Cursor but I am unable to get Claude Desktop to run it. I get the error “Could not attach to MCP simsy-py-mcp”. I have been unable to fix the issue and I am using Claude Desktop as the benchmark that others will be able to install and use my MCP once ready.
I have used the MCP python sdk and worked through the debugging guide and I am stuck so would appreciate any assistance.
The Claude log file shows this;
2025-04-14T06:35:44.148Z [simsy-mcp] [info] Initializing server…
2025-04-14T06:35:44.169Z [simsy-mcp] [info] Server started and connected successfully
2025-04-14T06:35:44.171Z [simsy-mcp] [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}
Server failed to start - check logs/server.log for details
Cleaning up…
2025-04-14T06:35:54.488Z [simsy-mcp] [info] Server transport closed
2025-04-14T06:35:54.488Z [simsy-mcp] [info] Client transport closed
2025-04-14T06:35:54.489Z [simsy-mcp] [info] Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. console.error('...') in JavaScript, print('...', file=sys.stderr) in python) and it will appear in this log.
2025-04-14T06:35:54.489Z [simsy-mcp] [error] Server disconnected. For troubleshooting guidance, please visit our debugging documentation {“context”:“connection”}
2025-04-14T06:35:54.490Z [simsy-mcp] [info] Client transport closed