Which MCP protocol versions and transports servers speak

See which protocol versions and transports the open MCP servers in this directory answered with, and which to support today. 263 open servers answered with 5 different protocol versions. First step: Read the protocol version your server returns in the handshake.

Steps

1. Read the protocol version your server returns in the handshake.
2. Serve Streamable HTTP; HTTP+SSE is deprecated in the 2026-07-28 revision.
3. List the versions you support in your server card.
4. Test with a client from each era before dropping an old version.

What the sources say

• The 2026-07-28 MCP revision deprecates HTTP+SSE with a window of at least twelve months. (modelcontextprotocol.io, read 4 November 2026)
• Servers on the 2026-07-28 revision MUST implement server/discover; earlier revisions open with an initialize handshake. (modelcontextprotocol.io, read 4 November 2026)
• Ora's server cards list supported protocol versions 2025-11-25 and 2025-06-18 for both of its MCP servers. (ora.ai, read 5 November 2026)
• Ora's integrations page says its server is compatible with clients that support protocol revisions through 2025-11-25. (ora.ai, read 5 November 2026)
• Ora's check for a modern transport gives credit to a server that speaks Streamable HTTP and not only the legacy transport. (ora.ai, read 5 November 2026)

What the open servers answered

Transports

A server that lists an older revision still works with clients from that era, and Ora's server cards list two revisions at once. How to put the list in a card and how Ora checks the transport.