Anthropic Messages API¶

SMG supports the Anthropic Messages API (/v1/messages), enabling applications to use Claude models through the gateway. Both HTTP proxy mode (forwarding to Anthropic's API) and gRPC mode (routing to local inference backends) are supported.

Endpoint¶

Create a message.

POST /v1/messages

For streaming responses, set "stream": true in the request body.

Request Example¶

curl http://localhost:30000/v1/messages \
  -H "Content-Type: application/json" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-sonnet-4-20250514",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": "What is the meaning of life?"}
    ]
  }'

Streaming¶

To receive responses as Server-Sent Events, set "stream": true:

curl http://localhost:30000/v1/messages \
  -H "Content-Type: application/json" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-sonnet-4-20250514",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": "What is the meaning of life?"}
    ],
    "stream": true
  }'

gRPC Backend¶

The Messages API works with gRPC backends such as SGLang and vLLM. When routing to a gRPC backend, SMG translates the Anthropic message format to the backend's native format and translates the response back.

Connection Modes¶

Features¶

• Streaming and non-streaming responses
• Tool use (via MCP integration)
• Extended thinking
• Multi-turn conversations