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The datetime Server Tool provides models with the current date and time. Instead of hardcoding dates in system prompts or relying on models’ training cutoffs, use this tool to give models accurate, real-time temporal awareness.

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Quick Start

{
  "model": "openai/gpt-5.4",
  "messages": [
    {"role": "user", "content": "What day of the week is today, and how many days until the end of the year?"}
  ],
  "tools": [
    {"type": "arouter", "arouter": {"id": "datetime"}}
  ]
}

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 day of the week is today, and how many days until the end of the year?"
    }
  ],
  tools: [
    { type: "arouter", arouter: { id: "datetime" } } as any,
  ],
});

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

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Configuration

{
  "tools": [
    {
      "type": "arouter",
      "arouter": {
        "id": "datetime",
        "timezone": "America/New_York"
      }
    }
  ]
}
ParameterTypeDefaultDescription
idstring—Must be "datetime"
timezonestring"UTC"IANA timezone identifier (e.g. "America/New_York", "Asia/Shanghai", "Europe/London")

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Tool Response Format

When the model invokes datetime, ARouter returns the following structure as the tool result: 
{
  "datetime": "2026-04-03T14:32:00Z",
  "date": "2026-04-03",
  "time": "14:32:00",
  "timezone": "UTC",
  "day_of_week": "Friday",
  "unix_timestamp": 1775319120
}

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Use Cases

Scheduling and planning: 
response = client.chat.completions.create(
    model="openai/gpt-5.4",
    messages=[{
        "role": "user",
        "content": "Create a 2-week project plan starting from today for building a REST API."
    }],
    tools=[
        {"type": "arouter", "arouter": {"id": "datetime", "timezone": "Asia/Shanghai"}}
    ],
)
Time-aware responses: 
response = client.chat.completions.create(
    model="anthropic/claude-sonnet-4.6",
    messages=[{
        "role": "user",
        "content": "Is it a good time to go for a morning run? I'm in Tokyo."
    }],
    tools=[
        {"type": "arouter", "arouter": {"id": "datetime", "timezone": "Asia/Tokyo"}}
    ],
)

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Pricing

The datetime tool is free — no additional charge beyond normal LLM token costs for the injected tool result.

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Next Steps