MCP Version 5 Removes Stateful Sessions, Adds OAuth and Extensions Framework
Anthropic released version 5 of the Model Context Protocol, replacing its stateful session model with a stateless request/response architecture. The spec adds OAuth 2.0 authorization and a versioned extensions framework for features like interactive UIs and long-running tasks. Adoption data shows over 400 million monthly SDK downloads and 950 MCP servers listed in Claude’s directory.