Models
December 19, 2025

Anthropic launches Bloom

Anthropic released Bloom, an open-source framework that generates and scores behavioral evaluations automatically, helping researchers measure model risks like deception, bias, and misalignment at scale.

Anthropic introduced Bloom, an open-source tool designed to automate behavioral safety evaluations for frontier models.

Bloom takes a target behavior (e.g., dishonesty, self-interest, bias) and generates diverse test scenarios, measuring both frequency and severity of that behavior in model responses. Anthropic claims Bloom evaluations correlate strongly with hand-labeled judgments and reliably differentiate baseline models from intentionally misaligned ones.

This is significant because safety evaluation has become a bottleneck: models evolve faster than manual testing can keep up. Bloom’s approach provides repeatable, scalable behavioral auditing that could become a standard layer in safety and governance workflows.

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Anthropic

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