Summary
One tool, and the limits are arguments to it rather than server configuration.
execute_js takes memory and timeout alongside the code, so the ceiling belongs to the call and a client can run an untrusted snippet tighter than a trusted one without restarting anything. The set is exactly this one capability: no file access, no package installation and no session that persists between calls appear in the tool surface.
What it is
A single-tool execution server that evaluates JavaScript in an isolated environment under caller-set limits.
What you get
- Isolated execution of a code string: execute_js runs the JavaScript you pass and returns its result.
- Bounded runs: the same call takes a memory limit and a timeout, so a snippet that loops or allocates without end is stopped by the sandbox rather than by the host.
Requirements
Nothing beyond the host the server runs on — the tool takes no account, key or external service, only the code and its limits.
Setup effort
One command — npx -y js-sandbox-mcp-server