mcp-path-validation-filesystem-mcp-server-on-windows-returns-access-de-3e63988d

THEN Ensure that the drive letter in the `mcp_config.json` path argument is uppercase (e.g., `C:\Users\...`). The server appears to canonicalize the allowed directory to uppercase, and lowercase drive letters in tool calls or config cause false positives. If the client (e.g., Cascade AI) sends lowercase paths, either normalize paths before calling or configure the server with uppercase and ensure the client also uses uppercase.

// Correct config to avoid case sensitivity:
{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "C:\\Users\\YourUser\\TestDoc"]
    }
  }
}