Messages

POST /v1/messages — Anthropic Messages format through SERV.

POST https://inference-api.openserv.ai/v1/messages

Anthropic Messages format. Accepts Claude and most other models in the catalog — see endpoint compatibility.

Request

Authorization · string · required

Bearer $SERV_API_KEY.

model · string · required

Model ID from the catalog, for example claude-haiku-4.5.

max_tokens · integer · required

Maximum number of tokens to generate. Required by the Messages format.

system · string · required

The system prompt. SERV requires one.

messages · array · required

The conversation so far. Each entry has a role (user or assistant) and content.

thinking · object

Extended thinking controls, for example { "type": "enabled", "budget_tokens": 1024 }.

tools · array

Tool definitions, in Anthropic format: { name, input_schema }.

tool_choice · string | object

"auto", "any", or { "type": "tool", "name": "..." }.

stop_sequences · array

Sequences that stop generation.

stream · boolean · default: "false"

Stream the response as server-sent events.

All other Anthropic Messages parameters are accepted and forwarded to the model.

Response

id · string

Unique identifier for the message.

type · string

Always "message".

role · string

Always "assistant".

model · string

The model used.

content · array

Output blocks. Find the block with type: "text" for the generated text.

stop_reason · string

Why generation ended. Common values: end_turn, max_tokens, stop_sequence, tool_use.

usage · object

Token counts: input_tokens, output_tokens.

curl

curl https://inference-api.openserv.ai/v1/messages \
  -H "Authorization: Bearer $SERV_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-haiku-4.5",
    "max_tokens": 1024,
    "system": "You answer in one sentence.",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

{
  "id": "msg_...",
  "type": "message",
  "role": "assistant",
  "model": "claude-haiku-4.5",
  "content": [{ "type": "text", "text": "Hello! How can I help?" }],
  "stop_reason": "end_turn",
  "usage": { "input_tokens": 16, "output_tokens": 7 }
}