What this model error usually means
Anthropic: Claude Opus 4.5 returning 400 / model capability unsupported means you should first confirm whether model ID anthropic/claude-opus-4.5 is visible for this Anthropic key, then separate permission, context, capability, rate limit, or route issues.
- Model: anthropic/claude-opus-4.5
- Provider: Anthropic
- Status code: 400