When something breaks in production, you need to answer three questions: what happened, how bad is it, and where did it go wrong? Logs, metrics, and traces each answer one of these. Spans are the pieces that make traces work. Together they are the core of observability.

Logs

Log — A …

Shipping an LLM app is the easy part. Knowing why it gave a wrong answer at 2 a.m. on a Tuesday is the hard part. Traditional software fails loudly with a stack trace. LLM apps fail quietly: the code runs, the API returns 200, and the answer is confidently …

Have You Ever Asked a Friend "Why Did You Do That?" and Gotten a Shrug?

That's basically what it feels like to debug an AI agent system.

You watch it mess up. You check the logs. The logs cheerfully tell you what happened — it called a tool, it got a …