The Sei MCP Server supports three transport modes for different integration scenarios. In most cases, stdio is the best choice, but understanding these modes is important if you need a remote MCP server or if your AI tool doesn’t support MCP. Each transport offers unique advantages depending on your use case and client requirements.

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Transport Overview

stdio

Default Mode Direct process communication via standard input/output streams.

streamable-http

HTTP API RESTful HTTP server with streaming capabilities for web integrations.

http-sse (deprecated)

Server-Sent Events HTTP with server-sent events (deprecated, use streamable-http instead).

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Choosing the Right Transport

Recommended for:
  • Claude Desktop, Cursor, Windsurf integrations
  • Local development and testing
  • Maximum performance requirements
Pros:
  • Fastest performance (no network overhead)
  • Automatic lifecycle management
  • Native MCP client support
Cons:
  • Limited to local process communication
  • No remote access capabilities
Security:
  • Process isolation (server runs as child process)
  • No network exposure (communication via local IPC)
  • Client-managed lifecycle
Recommended for:
  • Remote server deployments
  • Custom HTTP clients
  • Tools that don’t support MCP
  • Web applications
Pros:
  • Network accessible
  • Standard HTTP protocols
  • Scalable and load-balanceable
  • Works with any HTTP client
Cons:
  • Network latency overhead
  • Requires manual server management
  • Additional security considerations
Security:
  • Network exposure (server accessible over HTTP)
  • Consider implementing API keys or tokens
  • Configure CORS policies as needed
  • Restrict access to trusted networks
  • Use reverse proxy with HTTPS for production
Status: Deprecated - migrate to streamable-httpThis transport is no longer recommended for new implementations. Existing users should migrate to streamable-http for better performance and standards compliance.

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Configuration

Claude Desktop
{
  "mcpServers": {
    "sei": {
      "command": "npx",
      "args": ["-y", "@sei-js/mcp-server"]
    }
  }
}
Environment Variables
# stdio is the default, no configuration needed
SERVER_TRANSPORT=stdio  # Optional, this is default
npx @sei-js/mcp-server