Duplicated log lines when connecting to MCP servers

Bug Reports
1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

I am seeing duplicated logs when I look at the outputs from MCP servers that I am connecting to via stdio. It doesn’t seem to be a problem with the MCP servers that I am using, since I don’t see duplicated logs when I run the servers in VSCode and the problem is not specific to one MCP server.

Steps to Reproduce

When I connect to an MCP server, say the AWS documentation server like this:

"AWS Documentation": {
      "command": "uvx",
      "args": ["awslabs.aws-documentation-mcp-server@latest"],
      "env": {
        "FASTMCP_LOG_LEVEL": "DEBUG",
        "AWS_DOCUMENTATION_PARTITION": "aws"
      }
    }

I get duplicated logs as shown below (sometimes I get even more log lines because Cursor seem to establish multiple connections to the same MCP server on startup, but that problem was already reported here: MCP servers using a lot of CPU):

2025-10-16 13:28:31.072 [error] [10/16/25 13:28:31] INFO     Processing request of type            server.py:672
                             ListToolsRequest                                   

2025-10-16 13:28:31.072 [error] [10/16/25 13:28:31] INFO     Processing request of type            server.py:672
                             ListToolsRequest                                   

2025-10-16 13:28:31.074 [error]                     INFO     Processing request of type            server.py:672
                             ListPromptsRequest                                 

2025-10-16 13:28:31.074 [error]                     INFO     Processing request of type            server.py:672
                             ListPromptsRequest                                 

2025-10-16 13:28:31.075 [error]                     INFO     Processing request of type            server.py:672
                             ListResourcesRequest                               

2025-10-16 13:28:31.075 [error]                     INFO     Processing request of type            server.py:672
                             ListResourcesRequest

This is the output I am getting when I run the same MCP server in VSCode:

2025-10-16 13:28:08.012 [warning] [server stderr] [10/16/25 13:28:08] INFO     Processing request of type            server.py:672
2025-10-16 13:28:08.012 [warning] [server stderr]                              ListToolsRequest
2025-10-16 13:28:08.012 [warning] [server stderr]                     INFO     Processing request of type            server.py:672
2025-10-16 13:28:08.012 [warning] [server stderr]                              ListPromptsRequest
2025-10-16 13:28:08.013 [info] Discovered 3 tools

Expected Behavior

There shouldn’t be duplicated logs

Operating System

MacOS

Current Cursor Version (Menu → About Cursor → Copy)

Version: 1.7.44 (Universal)
VSCode Version: 1.99.3
Commit: 9d178a4■■■89981b62546448bb32920a8219a5d0
Date: 2025-10-10T15:43:37.500Z
Electron: 34.5.8
Chromium: 132.0.6834.210
Node.js: 20.19.1
V8: 13.2.152.41-electron.0
OS: Darwin arm64 24.6.0

Does this stop you from using Cursor

No - Cursor works, but with this issue

2

Hey, thanks for the report and the VSCode comparison, this helps confirm it’s a Cursor-specific logging issue.

The duplicate logs seem related to how Cursor handles MCP server stdio output. As you noted, it may be tied to the multiple-connection behavior that the team is already investigating.

I’ll pass this to the team for investigation. Since functionality isn’t blocked, you can continue using MCP servers while we look into it.

4

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