Claude Sonnet 5.5 joins Arena.ai Agent Arena and Battle Mode

Arena.ai has added Claude Sonnet 5.5 by AnthropicAI to Agent Arena. The model is also in Battle Mode for WebDev, Text, Vision, and Document.

In Agent Arena, models can use web search, filesystem, and terminal tools on long-horizon agentic tasks. Arena.ai says the leaderboard compares task outcomes with the average model using causal tracing.

Claude says Sonnet 5.5 is the second model in the Claude 5.5 family and a clear upgrade over Sonnet 5. It runs more than 30% faster and costs up to 30% less for most work.