Note: this piece is about context pruning for code review -- cutting the token bill by shrinking what the agent reads. It is not the same as building a full knowledge-graph MCP for bug discovery, which I wrote about separately. Different goal, different pipeline. This one is the small tool.
The first time I checked the token bill for a month of Claude Code reviews, I thought the invoice had a typo. It did not. I was paying to re-read a 40,000-file monorepo on every pull request, the same way a junior engineer might re-read the whole rulebook before answering a Slack thread.
I had been calling this "context engineering." It was bulk loading with a nicer name.
I rebuilt the review path around one rule: only show the agent what is within two hops of the diff. Token bill dropped between 8x and 49x depending on the repo. Review quality went up, not down.
Here is what the split looks like in practice, based on the twelve repos I have measured or seen measured:
