Directing agents is the easy half. The hard half is knowing which of their answers to trust.
I spent about two weeks fanning out research subagents in Claude Code, ten at a time, and the bottleneck was never getting them to produce output. A model is good at producing candidates and bad at knowing what counts as proof. So when ten background agents each return a confident wall of text, generation is not the problem. Verification is. And you cannot verify what you cannot see. By the time the last agent reports, the interesting details are buried in a transcript nobody is going to read.
agentrace reads the transcript for you.
The core idea: no instrumentation
The thing I like most about it is that there is nothing to add ahead of time. No wrapper, no SDK, no decorator around your agent calls. Claude Code already writes every session to disk at ~/.claude/projects/<slug>/<session-id>.jsonl, and that file already contains every Agent delegation and the result it returned. The data is on disk whether or not you planned to look at it, which means you can analyse the run you wish you had traced, after the fact.
