Claude Haiku 5.5 is an Anthropic AI model optimized for high-volume applications where latency, efficiency, and reasoning capability are important. Anthropic positions the model for workloads including classification, routing, information extraction, and subagent tasks. Adaptive thinking is enabled by default, allowing Claude Haiku 5.5 to determine when reasoning is useful and how much reasoning to apply to a request. Developers can configure the effort parameter to adjust the balance between response quality, processing speed, and cost. The model has a 1 million token context window, compared with 200,000 tokens for Claude Haiku 4.5, enabling it to process substantially larger prompts and datasets. Its maximum output length has also increased from 64,000 to 128,000 tokens, with thinking tokens counting toward the configured output limit. Claude Haiku 5.5 includes browser use capabilities through the Claude API and Google Cloud, expanding its usefulness for AI agents and workflows involving web interaction. The model uses the newer tokenizer shared with Claude 4.7 and later models, causing identical text to consume approximately 30% more tokens than on Claude Haiku 4.5, although the exact difference varies by content. Claude Haiku 5.5 is suited to developers and organizations building scalable AI applications, routing systems, extraction pipelines, subagent architectures, and other workloads that benefit from a combination of fast responses and configurable reasoning.