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Claude API adds model capability fields to discovery endpoint, reveals token and feature support
Claude · apifeature · docs.anthropic.com ↗

Models API Enhancement

Anthropic has expanded the Models API with machine-readable capability fields to help developers discover model specifications at runtime.

What's New

The GET /v1/models and GET /v1/models/{model_id} endpoints now return:

  • max_input_tokens: Maximum input context window for the model
  • max_tokens: Maximum output token length
  • capabilities object: Structured data on supported features

Developer Impact

Instead of hardcoding model specifications, developers can now query the API to automatically discover:

  • Which models support extended thinking
  • Context window sizes for long-horizon tasks
  • Token limits for request planning
  • Feature availability across model versions

This simplifies multi-model strategies and makes applications more resilient to future model updates. Applications can adapt dynamically as Anthropic releases new models without requiring code changes.