How to Configure MCP Servers in Claude Code?

This guide explains the complete process of configuring MCP Servers in Claude Code, helping you add filesystem, database, GitHub, and other tool capabilities.

Configuration File Location

Claude Code uses claude_desktop_config.json to configure MCP Servers. Location varies by OS:

macOS

~/Library/Application Support/Claude/claude_desktop_config.json

Windows

%APPDATA%/Claude/claude_desktop_config.json

Linux

~/.config/Claude/claude_desktop_config.json

Standard Configuration Structure

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/Users/username/Documents",
        "/Users/username/Downloads"
      ]
    },
    "postgres": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-postgres",
        "postgresql://localhost/mydb"
      ]
    },
    "github": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-github"
      ],
      "env": {
        "GITHUB_PERSONAL_ACCESS_TOKEN": "your_token_here"
      }
    }
  }
}

Configuration Fields

Field	Type	Required	Description
command	string	Yes	Launch command, e.g., npx, uvx, node
args	array	Yes	Command arguments array
env	object	No	Environment variables, e.g., API Token

Common MCP Server Examples

Filesystem

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/path/to/allowed/directory"
      ]
    }
  }
}

PostgreSQL

{
  "mcpServers": {
    "postgres": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-postgres",
        "postgresql://user:password@localhost:5432/dbname"
      ]
    }
  }
}

GitHub

{
  "mcpServers": {
    "github": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-github"
      ],
      "env": {
        "GITHUB_PERSONAL_ACCESS_TOKEN": "ghp_xxxxxxxxxxxx"
      }
    }
  }
}

Configuration Steps

1. Create/Edit config file

   # macOS example
   mkdir -p ~/Library/Application\ Support/Claude
   touch ~/Library/Application\ Support/Claude/claude_desktop_config.json
   

2. Add MCP Server config
   Use examples above to add your tools

3. Validate JSON

   cat ~/Library/Application\ Support/Claude/claude_desktop_config.json | jq
   

4. Restart Claude Code
   Completely quit Claude Code, then restart

5. Verify tools loaded
   Type /mcp in Claude Code to see loaded tools

Troubleshooting

JSON Format Error

• Symptom: Error on Claude Code startup
• Fix: Use jq or JSON validator

Path Error

• Symptom: Tool cannot access directory
• Fix: Check path exists, use absolute path

Permission Denied

• Symptom: File operation rejected
• Fix: Check filesystem permissions

Command Not Found

• Symptom: npx: command not found
• Fix: Ensure Node.js is installed and in PATH

Next Steps

• 📖 MCP Server Startup Failure Troubleshooting
• 🔧 Filesystem Tool Configuration
• 📁 PostgreSQL Tool Configuration