Inventory of how call_api works for different providers:

• Anthropic - requires different auth header and specialized headers for tool use
• AWS - very different, using SDK
• DeepSeek - pretty standard
• Gemini - different models, versions, streaming modes. Very different
• Mistral - standard
• OpenAI - slightly but different. The URL depends on version
• Perplexity - standard
• xAI - standard

All in all, 4 out of 8 could be implemented leveraging standard trait implementation.