What
MCP servers are outside programs that give Claude extra tools. Some of them can have their start deferred, meaning put off. When any deferred servers are configured, session setup now receives a startDeferredMcpServers step. It connects those servers under the label "claim" and returns their names.
Why
A server that was not connected when the session began can be brought in partway through instead of only at startup.
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
The finding does not say what triggers the step or what the "claim" label means.