Clarify model service prerequisite for CLI and Python API

Emphasize deploying and starting the OCR model service before running SDK examples.

README.md

@@ -139,6 +139,8 @@ To quickly try text-centric document understanding and structured information ex
 
 ### Use with the MiniCPM-OCR SDK
 
+> **Required before using either the CLI or Python API:** deploy and start the OCR model service first, and wait until it is ready to accept requests. The SDK examples below are clients of that running service; they do not deploy or start the OCR model service automatically.
+
 Use the official `minicpm-ocr` SDK to parse a local image or PDF. It detects layout
 with PP-DocLayoutV3, recognises each region, and saves structured JSON and Markdown
 in reading order.
@@ -151,16 +153,21 @@ pip install "minicpm-ocr[all]"
 
 Install minicpm-ocr for your platform using the
 [installation guide](https://github.com/OpenBMB/MiniCPM-OCR/blob/main/docs/minicpm_ocr_tutorial_en.md#1-set-up-the-sdk-environment).
-Before running the examples, start a compatible recognition service for
+
+#### Prerequisite: deploy and start the model service
+
+Before running either the CLI or Python API, deploy and start a vLLM recognition service for
 `openbmb/MiniCPM-OCR-1.0` following the
 [deployment guide](https://github.com/OpenBMB/MiniCPM-OCR/blob/main/docs/minicpm_ocr_tutorial_en.md#3-start-the-service).
 The examples assume a service at `http://127.0.0.1:8080`, served model name
 `minicpm-ocr`, and an NVIDIA GPU for layout detection. Match the endpoint, backend,
-and device to your deployment.
+and device to your deployment. Configure the service to listen on port `8080`
+and serve the model as `minicpm-ocr` to use the examples unchanged.
 
 #### CLI
 
-After starting the recognition service, save a local image as `demo.png` and run:
+**Start the model service described above and wait until it is ready before running this command.**
+Save a local image as `demo.png`, then run:
 
 ```bash
 minicpmvocr parse demo.png \
@@ -182,6 +189,9 @@ CPU layout detection. Run `minicpmvocr parse --help` for all CLI options.
 
 #### Python API
 
+**The model service described above must already be running before you execute this Python example.**
+Set `engine.server_url` and `engine.model_name` to match that service.
+
 Save a local image as `demo.png`, then run:
 
 ```python