Transport Modes

The server automatically selects the appropriate transport mode based on configuration.

Automatic Mode Selection

Configuration	Transport Mode	Endpoints	Use Case
PORT env var present	HTTP (Dual)	/sse and /mcp	Web clients, HTTP-based MCP
No PORT env var	stdio	N/A	CLI tools, direct MCP
stdio argument	stdio (forced)	N/A	Override PORT when set

HTTP Mode (Dual Transport)

When PORT is set, the server starts an Express HTTP server providing both endpoints simultaneously:

• /mcp — StreamableHTTP (recommended for modern clients)
• /sse — Server-Sent Events (backwards compatibility)

Features:

• Session management and reconnection
• Perfect for web-based MCP clients
• Supports TLS termination (direct or via reverse proxy)

stdio Mode

Direct stdin/stdout communication:

• No HTTP server required
• Optimal for command-line tools
• Lower resource usage
• Used by most desktop MCP clients (Claude Desktop, VS Code, Cursor)

Forcing stdio Mode

If PORT is set but you need stdio mode:

npx @structured-world/gitlab-mcp stdio

The stdio argument overrides the PORT environment variable.