What is the current MCP specification revision?

The current stable revision is 2026-07-28, released 2026-07-28. The largest revision since the protocol launched: the core becomes stateless (the initialize handshake and protocol-level sessions are removed), server/discover is introduced, Multi Round-Trip Requests replace server-initiated requests, routing headers and cacheable list results land, and a formal extensions framework and 12-month deprecation policy are adopted.

How often does the MCP specification change?

The protocol is versioned by revision date. 5 revisions are tracked here, each with its release date, headline changes, and per-entity adoption records.

MCP Specification Revisions

The Model Context Protocol has 5 specification revisions. The current stable revision is 2026-07-28, released 2026-07-28.

MCP 2026-07-28 - CURRENT · released 2026-07-28 · 2 support records
The largest revision since the protocol launched: the core becomes stateless (the initialize handshake and protocol-level sessions are removed), server/discover is introduced, Multi Round-Trip Requests replace server-initiated requests, routing headers and cacheable list results land, and a formal extensions framework and 12-month deprecation policy are adopted.
MCP 2025-11-25 - SUPERSEDED · released 2025-11-25 · 0 support records
Added OpenID Connect discovery, icons metadata, incremental scope consent, URL mode elicitation, tool calling in sampling, Client ID Metadata Documents as a recommended registration mechanism, and experimental tasks.
MCP 2025-06-18 - SUPERSEDED · released 2025-06-18 · 0 support records
Removed JSON-RPC batching, added structured tool output and elicitation, classified MCP servers as OAuth resource servers, and required RFC 8707 resource indicators plus the MCP-Protocol-Version header on HTTP.
MCP 2025-03-26 - SUPERSEDED · released 2025-03-26 · 0 support records
Added the OAuth 2.1 authorization framework, replaced the original HTTP+SSE transport with Streamable HTTP, and added JSON-RPC batching and tool annotations.
MCP 2024-11-05 - SUPERSEDED · released 2024-11-05 · 0 support records
The initial release of the Model Context Protocol specification: JSON-RPC 2.0 messages over stateful connections with capability negotiation, server features (resources, prompts, tools), the client sampling feature, and utilities for progress, cancellation, and logging.