Anthropic Messages - Hostlinku Docs

In addition to the OpenAI format, Hostlinku also provides endpoints compatible with the Anthropic Messages API. The official Anthropic SDK, Claude Code, Cursor, Cline, and other tools that support the Anthropic protocol can be used simply by changing the base URL—one API key and one Hostlinku balance cover both formats.

POST https://api.hostlinku.com/v1/messages
x-api-key: sk-isi-api-key-kamu
anthropic-version: 2023-06-01
Content-Type: application/json

Authentication accepts the x-api-key header (Anthropic style) or Authorization: Bearer sk-…. Each response includes the request-id / x-request-id header (Hostlinku request ID, in the format msg_…) and, for successful non-streaming responses, x-model.

Quick Setup

Step-by-step guides for each tool (Claude Code, Cline, and others) are available at IDE & Agent Integration. Claude Code

export ANTHROPIC_BASE_URL=https://api.hostlinku.com
export ANTHROPIC_API_KEY=sk-isi-api-key-kamu
export ANTHROPIC_MODEL=claude-sonnet-4-6
claude

Python (Anthropic’s official SDK)

import anthropic

client = anthropic.Anthropic(
    api_key="sk-isi-api-key-kamu",
    base_url="https://api.hostlinku.com",
)

message = client.messages.create(
    model="claude-haiku-4-5",
    max_tokens=256,
    messages=[{"role": "user", "content": "Jelaskan apa itu API gateway dalam dua kalimat."}],
)
print(message.content[0].text)
print(message.usage.input_tokens, message.usage.output_tokens)

Node.js

import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic({ apiKey: "sk-isi-api-key-kamu", baseURL: "https://api.hostlinku.com" });
const msg = await client.messages.create({
  model: "claude-haiku-4-5",
  max_tokens: 256,
  messages: [{ role: "user", content: "Halo!" }],
});

Body Parameters

Parameter	Type	Description
`model`	`string`	Required. Hostlinku model slug.
`messages`	`array`	Required. `{ role: "user" \| "assistant", content }`; `content` is a string or an array of blocks (`text`, `image`, `tool_use`, `tool_result`, …).
`max_tokens`	`integer`	Required (as per the Anthropic specification). Returns a `400` error if the model’s output limit is exceeded.
`system`	`string` \| `array`	System prompt; block arrays support `cache_control`.
`stream`	`boolean`	`true` for SSE (see below).
`temperature`	`number`	`0`–`1`.
`top_p`, `top_k`	`number`, `integer`	Alternative sampling.
`stop_sequences`	`string[]`	Maximum of 16.
`tools`, `tool_choice`	`array`, `any`	Uses the Anthropic tool format (including `input_schema`).
`thinking`	`object`	Extended thinking, e.g., `{ "type": "enabled", "budget_tokens": 1024 }`.
`metadata`	`object`	E.g., `{ "user_id": "…" }`.
`mcp_servers`, `context_management`, `output_format`	—	Passed through as-is (depending on model support).

Fields not in the list are discarded. An invalid body results in a 400 invalid_request_error response, with details for each field in error.details.issues.

Non-streaming response

{
  "id": "msg_…",
  "type": "message",
  "role": "assistant",
  "model": "claude-haiku-4-5",
  "content": [{ "type": "text", "text": "API gateway adalah …" }],
  "stop_reason": "end_turn",
  "stop_sequence": null,
  "usage": {
    "input_tokens": 30,
    "output_tokens": 55,
    "cache_creation_input_tokens": 0,
    "cache_read_input_tokens": 0,
    "cache_creation": { "ephemeral_5m_input_tokens": 0, "ephemeral_1h_input_tokens": 0 }
  },
  "hostlinku": { "cost": 0.00021, "currency": "🪙", "serviceMode": "performance", "latencyMs": 940 }
}

id and model are always Hostlinku’s public identifiers. The hostlinku block is an extension (the Anthropic SDK ignores it) containing the cost , Service Mode API key, and latency.

Streaming (`stream: true`)

The gateway streams SSE events using the Anthropic framing (event: + data:):

event: message_start
data: {"type":"message_start","message":{"id":"msg_…","type":"message","role":"assistant","model":"claude-haiku-4-5","content":[],"usage":{"input_tokens":22,"output_tokens":1,…}}}

event: content_block_start
data: {"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":"Apel"}}

event: content_block_stop
data: {"type":"content_block_stop","index":0}

event: message_delta
data: {"type":"message_delta","delta":{"stop_reason":"end_turn","stop_sequence":null},"usage":{"input_tokens":22,"output_tokens":7,…}}

event: message_stop
data: {"type":"message_stop"}

Note:

Final usage is recorded in message_delta; charges are calculated based on actual usage after message_stop.
If the stream fails midway, the gateway sends an event: error with {"type":"error","error":{"type":…,"message":…}} and do not send a fake message_stop.
Errors occurring before the first byte (insufficient balance, model not found, rate limit) are returned as A standard JSON response with the correct HTTP status code — the Anthropic SDK maps it to an exception (AuthenticationError, NotFoundError, RateLimitError, …).

Count tokens

POST https://api.hostlinku.com/v1/messages/count_tokens

Body: model, messages, optional system, tools, tool_choice, thinking. Response: { "input_tokens": 15 }. No charge.

Format error

{ "type": "error", "error": { "type": "authentication_error", "message": "API key tidak valid atau sudah dicabut." } }

HTTP	`error.type`	Common causes
400	`invalid_request_error`	Invalid body; `max_tokens` exceeds the model limit; model not available in Service Mode key.
401	`authentication_error`	Invalid, revoked, or expired API key.
402	`billing_error`	Insufficient balance or API key credit limit reached.
403	`permission_error`	Account suspended / access denied.
404	`not_found_error`	The model slug does not exist in the catalog.
429	`rate_limit_error`	Request limit reached.
503	`overloaded_error`	The model/upstream is currently unavailable — it is safe to retry.

Error messages never include the upstream provider’s identifier. A complete list of codes for the OpenAI format is available at Error.

​Quick Setup

​Body Parameters

​Non-streaming response

​Streaming (stream: true)

​Count tokens

​Format error