How to call Claude Code from a script without giving it tools or the global CLAUDE.md context?

I am using Claude Code Pro on Ubuntu 24 and need a stateless chat API that kids could type whatever’s on their mind into without nuking my system. I tried

claude -p 'What context do you have?' --system-prompt ''

and thought that --system-prompt '' would remove its access to ~claude/.claude/CLAUDE.md, but the output of the above command is my contact info plus the CLAUDE.md contents. Also it says it has tool access. For example:

claude -p 'Please create a 1-line lorem ipsum file in CWD.' --system-prompt ''

perfectly well modifies my filesystem.
Can any of this context or tool access be removed?