If you're building MCP servers that need to work with Claude Code's lifecycle hooks (Stop, PreCompact, UserPromptSubmit), this CLI audits whether your tools are safe to call in those contexts. It runs five test suites: idempotency (same input produces same output), side effects (read-only tools don't mutate state), latency (p50 under 30s, p95 under 60s), determinism (stable response shapes), and DSGVO (basic data flow documentation). You point it at any MCP server via a config file, it executes your tools multiple times with fixed inputs, and exits 0 for pass or 1 for failures. Requires Node 20+ and works over stdio transport. Built by StudioMeyer in Mallorca as part of their production MCP tooling.
claude mcp add --transport stdio io.studiomeyer-hook-conformance uvx hook-conformance