Just to be clear - the hook is deterministic, but the subagent running with an mcp server loaded is not - and for medium/large PRs, it can run out of context window or just forget what it is trying to do and get lazy and say 'Everything is good, ready to merge!' when in fact tests are failing or there are still unaddressed PR comments.

Sure, but that mcp still missed actionable comments that are marked as Out of Scope or Outside the PR - and this doesn't require having the context window loss of having another mcp instantiated, either. Anyway, give gtg a competitive look against the mcp - you should be able to see the difference