Symptoms
- An Anthropic body is sent to chat/completions, or an OpenAI body is sent to messages.
- The model is listed but the operation path is rejected.
Likely causes
- The client assumed every model supports every endpoint type.
- A copied example belongs to image, audio, video, embeddings, or rerank instead of chat.
How to diagnose
- Check supported_endpoint_types for the catalog record.
- Match the request schema to the final operation path.
- Reduce the request to the smallest example for that endpoint type.
Fixes
- Use only an endpoint advertised for the selected model.
- Switch either the client protocol or the model route so both agree.
- Keep task-specific payloads out of generic chat examples.
How to verify
A minimal request succeeds on the selected model’s advertised endpoint.