Developer Docs v2026.10

🔌 MCP 2026-07-28, Stateless by Protocol

Category: Developer Experience

The hosted server at /.well-known/mcp was already stateless in practice, but it only spoke the handshake-era revisions, and the MCP page opened with an initialize call captioned “Open a session”. The 2026-07-28 revision removed that handshake and protocol-level sessions, so the server and the page now follow it.

• Requests carry their protocol version and client capabilities in params._meta, mirrored in the MCP-Protocol-Version, Mcp-Method and Mcp-Name headers. Nothing has to be called first
• New server/discover method returns the supported versions, capabilities, server info and agent instructions
• Results carry resultType, identify the server in _meta, and list results are cacheable with ttlMs and cacheScope
• Headers that disagree with the body are refused with -32020, and an unknown version with -32022 and the list of supported versions
• Clients on 2025-11-25 and earlier keep working: initialize still negotiates a legacy version, and no session id is issued
• The MCP page’s first example is now an optional server/discover, and the tool call example is a self-contained request