The MCP 2026-07-28 release is the largest revision to the spec since launch, and the headline is that the protocol is going stateless. initialize is going away. The MCP session ID is going away for remote servers. Elicitation, sampling, and capability negotiation were all reworked so they still function without a session behind them.
Arcadians Nate Barbettini and Mateo Torres sat down with Caitie McCaffrey, an MCP core maintainer and engineer at Microsoft, and Sam Morrow, an MCP maintainer who runs GitHub’s MCP server, to work through why the maintainers took a breaking change this size and what it costs you to adopt it.
Caitie explains that she was highly motivated to pursue the change because of the numbers she was seeing at Microsoft. Across Microsoft’s servers, 40 to 50% of protocol messages were pure overhead (initialize, tool list, every single session) and roughly 90% of use cases weren’t using the stateful features they were paying for. She goes on to say that statefulness never really worked anyway, because no host implemented it correctly or implemented it the same way, so a server that relied on it worked in one client and broke in the next.
Sam’s perspective is just as practical, and he was surprised by the benefits. GitHub has already shipped the new protocol, has served more than 100,000 requests on it, and the migration was mostly deletion. “I found nothing but wins from the implementation,” he said.
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