claude-howto/04-mcp

MCP (Model Context Protocol) Examples

This folder contains example MCP server configurations for Claude Code.

What is MCP?

MCP (Model Context Protocol) enables Claude to access external tools, APIs, and real-time data sources. Unlike Memory, MCP provides live access to changing data.

Installation

Copy the appropriate configuration to your project's .claude/ directory:

cp github-mcp.json /path/to/your/project/.claude/mcp.json

Available MCP Configurations

1. GitHub MCP (github-mcp.json)

Access GitHub repositories, PRs, issues, and commits.

Setup:

export GITHUB_TOKEN="your_github_token"
cp github-mcp.json ~/.claude/mcp.json

Available Tools:

• list_prs - List all PRs in repository
• get_pr - Get PR details including diff
• create_pr - Create new PR
• list_issues - List all issues
• create_issue - Create new issue
• get_commit - Get commit details
• search_code - Search across codebase

Usage:

/mcp__github__list_prs completed:true last:7days
/mcp__github__get_pr 456
/mcp__github__create_issue "Bug in login form"

2. Database MCP (database-mcp.json)

Query PostgreSQL/MySQL databases.

Setup:

export DATABASE_URL="postgresql://user:pass@localhost/mydb"
cp database-mcp.json ~/.claude/mcp.json

Usage:

User: Fetch all users with more than 10 orders

Claude: I'll query your database:
SELECT u.*, COUNT(o.id) as order_count
FROM users u
LEFT JOIN orders o ON u.id = o.user_id
GROUP BY u.id
HAVING COUNT(o.id) > 10

3. Filesystem MCP (filesystem-mcp.json)

File operations on local filesystem.

Setup:

cp filesystem-mcp.json ~/.claude/mcp.json

Available Operations:

• List files
• Read file contents
• Write files
• Search in files
• Delete files

4. Multi-MCP (multi-mcp.json)

Configure multiple MCP servers simultaneously.

Setup:

export GITHUB_TOKEN="your_github_token"
export DATABASE_URL="postgresql://user:pass@localhost/mydb"
export SLACK_TOKEN="your_slack_token"
cp multi-mcp.json ~/.claude/mcp.json

Available MCP Servers

MCP Server	Purpose	Auth	Real-time
Filesystem	File operations	OS permissions	✅ Yes
GitHub	Repository management	OAuth	✅ Yes
Slack	Team communication	Token	✅ Yes
Database	SQL queries	Credentials	✅ Yes
Google Docs	Document access	OAuth	✅ Yes
Asana	Project management	API Key	✅ Yes
Stripe	Payment data	API Key	✅ Yes

Configuration Format

{
  "mcpServers": {
    "server-name": {
      "command": "npx",
      "args": ["@modelcontextprotocol/server-name"],
      "env": {
        "ENV_VAR": "${ENV_VAR}"
      }
    }
  }
}

Multi-MCP Workflow Example

Daily Report Generation

# Uses: GitHub MCP + Database MCP + Slack MCP + Filesystem MCP

## Step 1: Fetch GitHub Data
/mcp__github__list_prs completed:true last:7days
→ Output: 42 PRs merged

## Step 2: Query Database
SELECT COUNT(*) as sales, SUM(amount) as revenue
FROM orders WHERE created_at > NOW() - INTERVAL '1 day'
→ Output: 247 sales, $12,450 revenue

## Step 3: Generate Report
Combine data into HTML report

## Step 4: Save to Filesystem
Write report.html to /reports/

## Step 5: Post to Slack
Send summary to #daily-reports channel

✅ Report generated and posted

MCP vs Memory

graph TD
    A["Need external data?"]
    A -->|No| B["Use Memory"]
    A -->|Yes| C["Does it change frequently?"]
    C -->|No/Rarely| B
    C -->|Yes/Often| D["Use MCP"]

    B -->|Stores| E["Preferences<br/>Context<br/>History"]
    D -->|Accesses| F["Live APIs<br/>Databases<br/>Services"]

Environment Variables

Store sensitive credentials in environment variables:

# ~/.bashrc or ~/.zshrc
export GITHUB_TOKEN="ghp_xxxxxxxxxxxxx"
export DATABASE_URL="postgresql://user:pass@localhost/mydb"
export SLACK_TOKEN="xoxb-xxxxxxxxxxxxx"

Then reference them in MCP config:

{
  "env": {
    "GITHUB_TOKEN": "${GITHUB_TOKEN}"
  }
}

Security Best Practices

Do's ✅

• Use environment variables for credentials
• Rotate tokens regularly
• Use read-only tokens when possible
• Limit MCP server access scope
• Monitor MCP server usage

Don'ts ❌

• Don't hardcode credentials in config files
• Don't commit tokens to git
• Don't share tokens in team chats
• Don't use personal tokens for team projects
• Don't grant unnecessary permissions

Troubleshooting

MCP Server Not Found

# Install MCP server globally
npm install -g @modelcontextprotocol/server-github

Authentication Failed

# Verify environment variable is set
echo $GITHUB_TOKEN

# Re-export if needed
export GITHUB_TOKEN="your_token"

Connection Timeout

• Check network connectivity
• Verify API endpoint is accessible
• Check rate limits on API
• Try increasing timeout in config

Additional Resources

• MCP GitHub Repository
• MCP Protocol Specification
• Claude Code MCP Guide