When adding new models to configuration files, ensure all required configuration fields are populated, not just the model name in the running_models list. Models need complete configuration in both JSON (known_models.json) and YAML (provider files) with all necessary fields specified. Required fields typically include: - `n_ctx`: Context window size - `supports_tools`: Tool calling capability - `supports_multimodality`: Image/file support - `supports_agent`: Agent functionality - `tokenizer`: Tokenizer path - Additional provider-specific fields Example of complete configuration: ```yaml # In provider YAML file running_models: - claude-4 chat_models: claude-4: n_ctx: 200000 supports_tools: true supports_multimodality: true supports_clicks: true supports_agent: true supports_reasoning: anthropic tokenizer: hf://Xenova/claude-tokenizer ``` Incomplete configurations where only the model name is added to `running_models` without corresponding detailed configuration will result in runtime errors or unexpected behavior. Always cross-reference known_models.json to understand which configuration fields are required for proper model functionality.