Weave
A Weights & Biases toolkit to trace and evaluate agents and model-based applications. The Python SDK, Apache 2.0 licensed, turns on with `weave.init()`: it instruments the OpenAI Agents SDK, the Claude Agent SDK and Google ADK on its own, and `@weave.op` traces any function. Traces land in the hosted W&B service, which requires an account and a `WANDB_API_KEY` key. Weights & Biases has belonged to CoreWeave since May 2025 and is part of CoreWeave Forge; the W&B pricing page now redirects to CoreWeave.
Best for
- Following agents in the same place as training runs when the team already uses Weights & Biases
- Tracing an OpenAI Agents SDK, Claude Agent SDK or Google ADK agent without writing instrumentation