MCP Servers

MCP (Model Context Protocol) extends Claude with external tools — GitHub, Slack, databases, Playwright, and more.

Add a Server

# HTTP/hosted server
claude mcp add --transport http sentry https://mcp.sentry.dev/mcp

# Local stdio server (runs a process)
claude mcp add playwright -- npx -y @playwright/mcp@latest

# With environment variable
claude mcp add --env API_KEY=my-secret-key --transport http myapi https://api.example.com/mcp

# With auth header
claude mcp add --transport http --header "Authorization: Bearer TOKEN" myapi https://api.example.com/mcp

Manage Servers

claude mcp list                  # list all servers
claude mcp list --verbose        # include errors/warnings
claude mcp get sentry            # show details for one server
claude mcp remove sentry         # remove a server

In a session:

/mcp                             # manage MCP servers interactively

Scopes

claude mcp add --scope local   ...   # personal, this project (.claude.local.json)
claude mcp add --scope project ...   # team-shared (.mcp.json)
claude mcp add --scope user    ...   # all your projects (~/.claude.json)

Configuration Files

.mcp.json (project-shared)

{
  "mcpServers": {
    "playwright": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@playwright/mcp@latest"]
    },
    "sentry": {
      "type": "http",
      "url": "https://mcp.sentry.dev/mcp"
    },
    "local-db": {
      "type": "stdio",
      "command": "/usr/local/bin/db-mcp-server",
      "args": ["--db", "postgres://localhost/myapp"]
    }
  }
}

settings.json (inline)

{
  "mcpServers": {
    "github": {
      "type": "http",
      "url": "https://api.github.com/mcp"
    }
  }
}

Transport Types

Type	When to use	Config
http	Hosted/cloud services	url field
stdio	Local processes	command + args

OAuth Authentication

claude mcp add --transport http github https://api.github.com/mcp
/mcp
# Select the server → Authenticate

Tool Naming Convention

MCP tools appear as mcp__<server>__<tool>, e.g.:

• mcp__github__create_issue
• mcp__slack__send_message
• mcp__playwright__screenshot

Use in permissions:

{
  "permissions": {
    "allow": ["mcp__github__*"],
    "deny": ["mcp__slack__delete_*"]
  }
}

Popular MCP Servers

Server	Install command
Playwright (browser)	claude mcp add playwright -- npx -y @playwright/mcp@latest
GitHub	claude mcp add --transport http github https://api.github.com/mcp
Filesystem	claude mcp add fs -- npx -y @modelcontextprotocol/server-filesystem /path
Postgres	claude mcp add pg -- npx -y @modelcontextprotocol/server-postgres

🧠 Quick Recall

• Trick: “MCP = a USB port for AI — plug a tool in, Claude gains the ability.”

👨‍🏫 Teach It

• Show: /mcp → connect the GitHub server → use one tool on a real repo.
• They’ll trip on: “missing” tools that are just deferred — tool search loads schemas on demand.

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Learning path: ⬅ 24-hooks-real-examples.md · Index · ➡ 26-mcp-real-examples.md