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MCP servers communicate with clients using different transport protocols. The mcp-use client supports multiple connection types, each optimized for different use cases and deployment scenarios.

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Overview

The client supports three primary connection types:
  • STDIO: Local process communication via standard input/output
  • HTTP/SSE: Remote servers via HTTP with Server-Sent Events
  • WebSocket: Bidirectional streaming communication
The connection type is automatically detected based on your server configuration. You don’t need to specify it explicitly - just provide the appropriate parameters (command for STDIO, url for HTTP/WebSocket).

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STDIO (Standard Input/Output)

STDIO connections launch and manage MCP servers as local child processes, communicating through standard input and output streams.

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When to Use STDIO

  • Local development: Testing servers on your local machine
  • Security-sensitive operations: No network exposure required
  • File system access: Direct access to local files and resources
  • Simple deployment: No need for network configuration

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Characteristics

  • Servers run as child processes
  • Communication via stdin/stdout
  • Automatic process lifecycle management
  • Zero network latency
  • No external dependencies

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Configuration Example:

{
  "mcpServers": {
    "stdio_server": {
      "command": "npx",
      "args": ["@my-mcp/server"],
      "env": {}
    }
  }
}

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HTTP/SSE (Server-Sent Events)

HTTP connections communicate with MCP servers over standard HTTP/HTTPS protocols, using Server-Sent Events for real-time updates.

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When to Use HTTP

  • Remote servers: Connecting to servers hosted elsewhere
  • Production deployment: Servers behind load balancers or API gateways
  • Authentication: Servers requiring OAuth or API key authentication
  • Scalability: Multiple clients connecting to the same server

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Characteristics

  • Servers accessible via HTTP(S) endpoints
  • Support for custom headers (authentication, etc.)
  • Compatible with standard web infrastructure
  • Server-Sent Events for notifications

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Configuration Example:

{
  "mcpServers": {
    "http_server": {
      "url": "http://localhost:3000",
      "headers": {
        "Authorization": "Bearer ${AUTH_TOKEN}"
      }
    }
  }
}

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Connection Type Selection

The client automatically detects the appropriate connection type based on your configuration:
ConfigurationConnection TypeUse Case
command + argsSTDIOLocal process servers
url: http://...HTTP/SSERemote HTTP servers
url: ws://...WebSocketWebSocket servers
Automatic Detection: You never need to specify the connection type explicitly. The client analyzes your configuration and selects the appropriate transport protocol automatically.

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Best Practices

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For Development

Use STDIO connections for local development:
  • Faster iteration with direct process control
  • No network configuration needed
  • Easy debugging with process logs

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For Production

Use HTTP connections for production deployments:
  • Better scalability and load distribution
  • Support for authentication and authorization
  • Compatible with existing infrastructure
  • Easier monitoring and logging

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Security Considerations

  • STDIO: Most secure, no network exposure
  • HTTP: Use HTTPS in production, implement authentication
  • WebSocket: Use WSS (WebSocket Secure) for encrypted connections

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Next Steps

Client Configuration

Learn about all configuration options

Multi-Server Setup

Connect to multiple servers simultaneously

Authentication

Secure your connections with OAuth

Sandbox Mode

Secure execution environment for code