Server Tools

Server Tools are capabilities that ARouter executes on behalf of models during inference. Unlike user-defined function calling (where your code runs the function), Server Tools are handled entirely by ARouter — the model decides when to invoke them, ARouter executes them, and the results are injected back into the conversation automatically.

Server Tools are currently in beta. The interface is stable but additional tools are being added.

Available Server Tools

Tool ID	Description	Pricing
`web_search`	Search the web and return structured results with citations	Per search query
`datetime`	Return the current date and time in any timezone	Free

Server Tools vs Plugins vs User-Defined Tools

	Server Tools	Plugins	User-Defined Tools
Who executes?	ARouter	ARouter	Your application
Model controls invocation?	Yes	No (applied every request)	Yes
Structured citations?	Yes	Yes (web only)	N/A
Available in streaming?	Yes	Yes	Yes
Configuration	Per-request in `tools` array	Per-request in `plugins` array	Per-request in `tools` array

Use Server Tools when you want the model to decide whether and when to search, rather than forcing a search on every request.

How Server Tools Work

The entire tool execution cycle happens server-side. Your application receives the final response with results already incorporated.

Quick Start

Add Server Tools to any chat completion request via the tools array using the arouter: namespace:

{
  "model": "openai/gpt-5.4",
  "messages": [
    {"role": "user", "content": "What are the top AI news stories today?"}
  ],
  "tools": [
    {"type": "arouter", "arouter": {"id": "web_search"}}
  ]
}

TypeScript
Python
cURL

import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://api.arouter.ai/v1",
  apiKey: "lr_live_xxxx",
});

const response = await client.chat.completions.create({
  model: "openai/gpt-5.4",
  messages: [
    { role: "user", content: "What are the top AI news stories today?" }
  ],
  tools: [
    { type: "arouter", arouter: { id: "web_search" } } as any,
  ],
});

console.log(response.choices[0].message.content);

from openai import OpenAI

client = OpenAI(
    base_url="https://api.arouter.ai/v1",
    api_key="lr_live_xxxx",
)

response = client.chat.completions.create(
    model="openai/gpt-5.4",
    messages=[
        {"role": "user", "content": "What are the top AI news stories today?"}
    ],
    tools=[
        {"type": "arouter", "arouter": {"id": "web_search"}}
    ],
    extra_body={},
)

print(response.choices[0].message.content)

curl https://api.arouter.ai/v1/chat/completions \
  -H "Authorization: Bearer lr_live_xxxx" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5.4",
    "messages": [
      {"role": "user", "content": "What are the top AI news stories today?"}
    ],
    "tools": [
      {"type": "arouter", "arouter": {"id": "web_search"}}
    ]
  }'

Combining Multiple Server Tools

You can enable multiple Server Tools in a single request. The model will choose which to invoke based on the user’s query:

{
  "model": "openai/gpt-5.4",
  "messages": [
    {"role": "user", "content": "What important AI events happened this week?"}
  ],
  "tools": [
    {"type": "arouter", "arouter": {"id": "web_search"}},
    {"type": "arouter", "arouter": {"id": "datetime"}}
  ]
}

Combining with User-Defined Tools

Server Tools can coexist with your own function definitions:

{
  "model": "openai/gpt-5.4",
  "messages": [{"role": "user", "content": "..."}],
  "tools": [
    {"type": "arouter", "arouter": {"id": "web_search"}},
    {
      "type": "function",
      "function": {
        "name": "get_user_data",
        "description": "Get data from our internal database",
        "parameters": {...}
      }
    }
  ]
}

ARouter handles the arouter type tools; your application handles the function type tools.

Usage Tracking

Server Tool usage is tracked in the usage field:

{
  "usage": {
    "prompt_tokens": 450,
    "completion_tokens": 210,
    "total_tokens": 660,
    "cost": 0.00234,
    "server_tool_calls": {
      "web_search": 2
    }
  }
}

Next Steps

Web Search Tool — Full configuration reference for search engines, domain filtering, and pricing
Datetime Tool — Inject current time into model context
Migrating from Web Plugin — How to migrate from the deprecated web plugin

Get Started

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Available Server Tools

Server Tools vs Plugins vs User-Defined Tools

How Server Tools Work

Quick Start

Combining Multiple Server Tools

Combining with User-Defined Tools

Usage Tracking

Next Steps

​Available Server Tools

​Server Tools vs Plugins vs User-Defined Tools

​How Server Tools Work

​Quick Start

​Combining Multiple Server Tools

​Combining with User-Defined Tools

​Usage Tracking

​Next Steps

Available Server Tools

Server Tools vs Plugins vs User-Defined Tools

How Server Tools Work

Quick Start

Combining Multiple Server Tools

Combining with User-Defined Tools

Usage Tracking

Next Steps