mcp-rubber-duck

The server employs robust security measures, including extensive use of environment variables for secrets, a `SafeLogger` to redact sensitive data, and `JSON.parse` for LLM outputs which safely handles malformed JSON without code execution. The `FunctionBridge` facilitates calls to external MCP servers, including `stdio` commands which are configured by the operator, not dynamically generated from user input. Argument validation using `Ajv` and an `ApprovalService` (configurable for 'always', 'trusted', or 'never' modes, with session-based memory) provide strong defenses against malicious tool calls, requiring human intervention for untrusted actions. The overall architecture is designed with security in mind for its intended use case, with the primary remaining risk lying in potential misconfiguration of `stdio` commands by the operator.