Unclear It is not clear whether another condition, besides the environment variable, also has to be met before the remembered list is reused.
An MCP server is an outside program that gives Claude Code extra tools. Claude Code asks each server for its list of tools. It now remembers each server's list, along with a fingerprint of the server's configuration and of the tools it returned.
If you set the environment variable CLAUDE_CODE_MCP_SKIP_UNCHANGED_RELIST to exactly true, Claude Code reuses the remembered list when nothing has changed within a time window. It does not rebuild the list. An environment variable is a named value you set in your shell before starting Claude Code. Any other value leaves the old behaviour in place.
This saves repeated work fetching and rebuilding MCP tool lists, but only for people who set the variable.
It is not clear whether another condition, besides the environment variable, also has to be met before the remembered list is reused.