chore: native files and openai responses docs

docs/en/concepts/llms.mdx

@@ -207,6 +207,37 @@ In this section, you'll find detailed examples that help you select, configure,
     | o3-mini             | 200,000 tokens   | Lightweight reasoning model                   |
     | o4-mini             | 200,000 tokens   | Next-gen efficient reasoning                  |
 
+    **Responses API:**
+
+    OpenAI offers two APIs: Chat Completions (default) and the newer Responses API. The Responses API was designed from the ground up with native multimodal support—text, images, audio, and function calls are all first-class citizens. It provides better performance with reasoning models and supports additional features like auto-chaining and built-in tools.
+
+    ```python Code
+    from crewai import LLM
+
+    # Use the Responses API instead of Chat Completions
+    llm = LLM(
+        model="openai/gpt-4o",
+        api="responses",  # Enable Responses API
+        store=True,  # Store responses for multi-turn (optional)
+        auto_chain=True,  # Auto-chain for reasoning models (optional)
+    )
+    ```
+
+    **Responses API Parameters:**
+    - `api`: Set to `"responses"` to use the Responses API (default: `"completions"`)
+    - `instructions`: System-level instructions (Responses API only)
+    - `store`: Whether to store responses for multi-turn conversations
+    - `previous_response_id`: ID of previous response for multi-turn
+    - `include`: Additional data to include in response (e.g., `["reasoning.encrypted_content"]`)
+    - `builtin_tools`: List of OpenAI built-in tools: `"web_search"`, `"file_search"`, `"code_interpreter"`, `"computer_use"`
+    - `parse_tool_outputs`: Return structured `ResponsesAPIResult` with parsed built-in tool outputs
+    - `auto_chain`: Automatically track and use response IDs for multi-turn conversations
+    - `auto_chain_reasoning`: Track encrypted reasoning items for ZDR (Zero Data Retention) compliance
+
+    <Tip>
+      Use the Responses API for new projects, especially when working with reasoning models (o1, o3, o4) or when you need native multimodal support for [files](/en/concepts/files).
+    </Tip>
+
     **Note:** To use OpenAI, install the required dependencies:
     ```bash
     uv add "crewai[openai]"