A skill is a saved set of instructions Claude can reuse. Claude Code has a tool that suggests new skills when you keep repeating the same procedure. When that tool names a new skill, the name may no longer contain "claude" or "anthropic", and it must be 64 characters or fewer.
The check first converts lookalike characters to their standard form (NFKC normalisation) and makes the name lowercase, so capital letters or unusual characters cannot get around it. A rejected name gets this message back: "name contains "claude" or "anthropic", which a saved skill's name cannot include. Call again with a name that leaves those words out."
A saved skill's name cannot contain those words anyway. The suggestion tool now catches this when it names the skill and asks for a new name, so you do not end up with a suggestion that cannot be saved.