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MCP Error Decoder

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Category:
Security & SandboxHigh

Filesystem MCP: Permission Denied / Outside Root Sandbox

Symptom

Filesystem server returns error: Access denied to path outside allowed directory boundaries.

Root Cause

The tool attempted to read or write a file outside the directories specified in the server arguments list.

Remediation & Quick Fix

Add the directory or parent directory to the args array in your client configuration.

OS Diagnostic Commands:
mac
# Check directory permissions:
ls -la /path/to/target
windows
# Check directory permissions:
Get-Acl -Path C:\path\to\target
linux
# Check directory permissions:
ls -la /path/to/target
Verified Configuration Example:
{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "C:/Projects/main-app",
        "C:/Projects/shared-libs"
      ]
    }
  }
}