What
MCP (Model Context Protocol) servers are add-on services that give Claude Code extra tools and data. They often send long lists one page at a time. Each page includes a marker that says where the next page starts.
- Claude Code now remembers every page marker it has sent while reading a list. If the server sends one it has already seen, Claude Code stops reading. It logs the warning "returned a nextCursor already sent in this walk". Before, only a fixed page limit stopped it.
- Connection errors are now judged temporary, and worth retrying, only for network problems such as a reset or closed connection, or for the message patterns already recognised. An error that carries an HTTP status or code from 100 to 599, or a negative number, is no longer treated as temporary.
- In sessions that prepare no output formats for MCP tools, Claude Code now accepts tool output without checking its format.
Why
A misbehaving MCP server can no longer keep Claude Code reading the same pages over and over. Errors that will not fix themselves, such as an HTTP error response, are no longer retried for nothing.