MCP Server Styles - Char

This page explains the major MCP server styles and the tradeoffs between them.

Why This Matters

Most integration issues come from transport mismatch:

local subprocess workflows expect stdio
hosted/shared workflows expect HTTP transports
some clients still use older SSE-compatible remote flows

Style Comparison

Style	Transport	Where it runs	Typical auth	Best use case	Official references
Local subprocess server	`stdio`	Local machine (spawned process)	Usually local trust boundary; optional server auth	Browser automation and local dev tooling	MCP transports, Claude Code MCP
Remote MCP server (modern)	Streamable HTTP	Remote service	Bearer/session/OAuth (server-defined)	Shared hosted tools and multi-user environments	MCP transports, Claude Code MCP
Remote MCP server (legacy compatibility)	SSE + POST fallback	Remote service	HTTP auth (server-defined)	Backward compatibility with older client/server behavior	MCP transports
Connector-style remote usage	Remote HTTP MCP only	Remote service reachable by API provider	OAuth or bearer token via connector config	Tool access in API-based agent workflows	Anthropic MCP connector
Registry-discovered ecosystem servers	Varies (`stdio` and HTTP)	Local or hosted	Server-defined	Discovering existing production/community servers	MCP Registry, MCP servers repo, servers README

How To Choose Quickly

Use stdio when the tool must run locally and you control the machine.
Use Streamable HTTP when the server is shared, hosted, or multi-tenant.
Use legacy SSE mode only when a required client/server still depends on it.
Use connector-style remote MCP when an API provider requires remote-only integration.

Security Notes

Validate Origin headers for browser-based transports and avoid exposing local servers beyond trusted boundaries.
Prefer binding local HTTP listeners to loopback (localhost) unless you explicitly need network exposure.
Treat access tokens as bearer credentials and store/forward them only over TLS.
Keep remote MCP endpoints authenticated by default; avoid unauthenticated public tool surfaces.

Authoritative guidance: MCP transports + security considerations