Workspace level mcp.json execution context

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1

When I heard of project level mcp.json, I immediately thought of transforming development process when the project and assistant for it can evolve together in the same repository.

I did few experiments today with FastMCP, and results were less than satisfying. I was bashing my head why is my Hello World MCP server (run locally with uv run fastmcp run server.py) does not hookup to Cursor, until I tried running pwd as a command. In MCP logs I saw that pwd output is not at all my current workspace path, it is a Cursor user folder on Windows. Quite unexpected to say the least, and I found no workaround. I eventually made it work with starting my server in remote mode, and hooking up Cursor to a URL, but it is a hacky and fragile solution. Local script should work through stdio, its what it is for.

Its quite a deal breaker, as I am looking for a coding assistant fully integrated with local and remote MCPs. I advocated for using Cursor in my company, and we just finished trial. I was planning to push for wide integration of project specific MCP to automate development routines, and this problem blocks me.

2

Hi can you tell me more about what you’re looking for here? Is the problem that its running in the wrong environment (ie its in your WSL or remote-ssh env when you want it in your local env) or that the PATH env var is wrong?

If the latter, we offer a WORKSPACE_FOLDER_PATHS env var that should give you the workspace folders.

3

Hi @msfeldstein ! Its the latter, and I am not sure this variable is working, or am I using it wrong. See my example:

mcp.json:

{
  "mcpServers": {
    "showWorkspacePaths": {
      "command": "uv",
      "args": [
        "run",
        "--directory",
        "$WORKSPACE_FOLDER_PATHS",
        "fastmcp",
        "run",
        "mcp/mcp_server.py:mcp"
      ]
    }
  }
}

mcp_server.py:

from fastmcp import FastMCP

# Create MCP server instance
mcp = FastMCP("Hello World MCP Server")

@mcp.tool()
def say_hello(name: str = "World") -> str:
    """
    Say hello to someone.
    
    Args:
        name: Name of the person to greet (defaults to "World")
    
    Returns:
        A greeting message
    """
    return f"Hello, {name}! Welcome to the Hello World MCP Server! 🌍"

I am not seeing any tools for this server, and it there are not much in logs:

2025-06-03 21:39:40.291 [info] aths: Starting new stdio process with command: uv run --directory $WORKSPACE_FOLDER_PATHS fastmcp run mcp/mcp_server.py:mcp

2025-06-03 21:39:40.296 [info] aths: Client closed for command

2025-06-03 21:39:40.299 [info] near: Handling ListOfferings action

2025-06-03 21:39:40.299 [error] near: No server info found

2025-06-03 21:39:40.301 [info] tant: Handling ListOfferings action

2025-06-03 21:39:40.301 [error] tant: No server info found

2025-06-03 21:39:40.303 [info] tHub: Handling ListOfferings action

2025-06-03 21:39:40.303 [error] tHub: No server info found

2025-06-03 21:39:40.306 [info] aths: Handling ListOfferings action

2025-06-03 21:39:40.306 [error] aths: No server info found

I tested uv run --directory %my dir% fastmcp run mcp/mcp_server.py:mcp and it works well, I also debugged this server. But I can’t make it work in the Cursor.