Create a chat completion

Create chat completion

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    model: 'openai/gpt-5-nano',
    stream: false,
    messages: [{role: 'user', content: 'What is the current datetime in Europe/London?'}],
    tools: [{type: 'gateway:datetime', parameters: {timezone: 'Europe/London'}}],
    tool_choice: 'auto'
  })
};

fetch('https://api.phaseo.app/v1/chat/completions', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://api.phaseo.app/v1/chat/completions"

payload = {
    "model": "openai/gpt-5-nano",
    "stream": False,
    "messages": [
        {
            "role": "user",
            "content": "What is the current datetime in Europe/London?"
        }
    ],
    "tools": [
        {
            "type": "gateway:datetime",
            "parameters": { "timezone": "Europe/London" }
        }
    ],
    "tool_choice": "auto"
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

curl --request POST \
  --url https://api.phaseo.app/v1/chat/completions \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "model": "openai/gpt-5-nano",
  "stream": false,
  "messages": [
    {
      "role": "user",
      "content": "What is the current datetime in Europe/London?"
    }
  ],
  "tools": [
    {
      "type": "gateway:datetime",
      "parameters": {
        "timezone": "Europe/London"
      }
    }
  ],
  "tool_choice": "auto"
}
'

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.phaseo.app/v1/chat/completions"

	payload := strings.NewReader("{\n  \"model\": \"openai/gpt-5-nano\",\n  \"stream\": false,\n  \"messages\": [\n    {\n      \"role\": \"user\",\n      \"content\": \"What is the current datetime in Europe/London?\"\n    }\n  ],\n  \"tools\": [\n    {\n      \"type\": \"gateway:datetime\",\n      \"parameters\": {\n        \"timezone\": \"Europe/London\"\n      }\n    }\n  ],\n  \"tool_choice\": \"auto\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.phaseo.app/v1/chat/completions")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"model\": \"openai/gpt-5-nano\",\n  \"stream\": false,\n  \"messages\": [\n    {\n      \"role\": \"user\",\n      \"content\": \"What is the current datetime in Europe/London?\"\n    }\n  ],\n  \"tools\": [\n    {\n      \"type\": \"gateway:datetime\",\n      \"parameters\": {\n        \"timezone\": \"Europe/London\"\n      }\n    }\n  ],\n  \"tool_choice\": \"auto\"\n}")
  .asString();

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.phaseo.app/v1/chat/completions",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'model' => 'openai/gpt-5-nano',
    'stream' => false,
    'messages' => [
        [
                'role' => 'user',
                'content' => 'What is the current datetime in Europe/London?'
        ]
    ],
    'tools' => [
        [
                'type' => 'gateway:datetime',
                'parameters' => [
                                'timezone' => 'Europe/London'
                ]
        ]
    ],
    'tool_choice' => 'auto'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

require 'uri'
require 'net/http'

url = URI("https://api.phaseo.app/v1/chat/completions")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"model\": \"openai/gpt-5-nano\",\n  \"stream\": false,\n  \"messages\": [\n    {\n      \"role\": \"user\",\n      \"content\": \"What is the current datetime in Europe/London?\"\n    }\n  ],\n  \"tools\": [\n    {\n      \"type\": \"gateway:datetime\",\n      \"parameters\": {\n        \"timezone\": \"Europe/London\"\n      }\n    }\n  ],\n  \"tool_choice\": \"auto\"\n}"

response = http.request(request)
puts response.read_body

{
  "id": "<string>",
  "nativeResponseId": "<string>",
  "object": "<string>",
  "created": 123,
  "model": "<string>",
  "provider": "<string>",
  "choices": [
    {
      "index": 123,
      "message": {
        "role": "system",
        "content": "<string>",
        "name": "<string>",
        "tool_calls": [
          {
            "id": "<string>",
            "type": "function",
            "function": {
              "name": "<string>",
              "arguments": "<string>",
              "description": "<string>",
              "parameters": {}
            }
          }
        ],
        "images": [
          {
            "type": "image_url",
            "image_url": {
              "url": "<string>"
            },
            "mime_type": "<string>"
          }
        ],
        "audios": [
          {
            "type": "audio_url",
            "audio_url": {
              "url": "<string>"
            },
            "mime_type": "<string>",
            "format": "wav"
          }
        ],
        "tool_call_id": "<string>"
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 123,
    "completion_tokens": 123,
    "total_tokens": 123,
    "server_tool_use": {
      "datetime_requests": 1,
      "web_search_requests": 1,
      "subagent_requests": 1,
      "fusion_requests": 1,
      "search_models_requests": 1,
      "web_fetch_requests": 1,
      "advisor_requests": 1,
      "image_generation_requests": 1,
      "apply_patch_requests": 1
    }
  }
}

POST

chat

completions

Create chat completion

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    model: 'openai/gpt-5-nano',
    stream: false,
    messages: [{role: 'user', content: 'What is the current datetime in Europe/London?'}],
    tools: [{type: 'gateway:datetime', parameters: {timezone: 'Europe/London'}}],
    tool_choice: 'auto'
  })
};

fetch('https://api.phaseo.app/v1/chat/completions', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://api.phaseo.app/v1/chat/completions"

payload = {
    "model": "openai/gpt-5-nano",
    "stream": False,
    "messages": [
        {
            "role": "user",
            "content": "What is the current datetime in Europe/London?"
        }
    ],
    "tools": [
        {
            "type": "gateway:datetime",
            "parameters": { "timezone": "Europe/London" }
        }
    ],
    "tool_choice": "auto"
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

curl --request POST \
  --url https://api.phaseo.app/v1/chat/completions \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "model": "openai/gpt-5-nano",
  "stream": false,
  "messages": [
    {
      "role": "user",
      "content": "What is the current datetime in Europe/London?"
    }
  ],
  "tools": [
    {
      "type": "gateway:datetime",
      "parameters": {
        "timezone": "Europe/London"
      }
    }
  ],
  "tool_choice": "auto"
}
'

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.phaseo.app/v1/chat/completions"

	payload := strings.NewReader("{\n  \"model\": \"openai/gpt-5-nano\",\n  \"stream\": false,\n  \"messages\": [\n    {\n      \"role\": \"user\",\n      \"content\": \"What is the current datetime in Europe/London?\"\n    }\n  ],\n  \"tools\": [\n    {\n      \"type\": \"gateway:datetime\",\n      \"parameters\": {\n        \"timezone\": \"Europe/London\"\n      }\n    }\n  ],\n  \"tool_choice\": \"auto\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.phaseo.app/v1/chat/completions")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"model\": \"openai/gpt-5-nano\",\n  \"stream\": false,\n  \"messages\": [\n    {\n      \"role\": \"user\",\n      \"content\": \"What is the current datetime in Europe/London?\"\n    }\n  ],\n  \"tools\": [\n    {\n      \"type\": \"gateway:datetime\",\n      \"parameters\": {\n        \"timezone\": \"Europe/London\"\n      }\n    }\n  ],\n  \"tool_choice\": \"auto\"\n}")
  .asString();

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.phaseo.app/v1/chat/completions",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'model' => 'openai/gpt-5-nano',
    'stream' => false,
    'messages' => [
        [
                'role' => 'user',
                'content' => 'What is the current datetime in Europe/London?'
        ]
    ],
    'tools' => [
        [
                'type' => 'gateway:datetime',
                'parameters' => [
                                'timezone' => 'Europe/London'
                ]
        ]
    ],
    'tool_choice' => 'auto'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

require 'uri'
require 'net/http'

url = URI("https://api.phaseo.app/v1/chat/completions")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"model\": \"openai/gpt-5-nano\",\n  \"stream\": false,\n  \"messages\": [\n    {\n      \"role\": \"user\",\n      \"content\": \"What is the current datetime in Europe/London?\"\n    }\n  ],\n  \"tools\": [\n    {\n      \"type\": \"gateway:datetime\",\n      \"parameters\": {\n        \"timezone\": \"Europe/London\"\n      }\n    }\n  ],\n  \"tool_choice\": \"auto\"\n}"

response = http.request(request)
puts response.read_body

{
  "id": "<string>",
  "nativeResponseId": "<string>",
  "object": "<string>",
  "created": 123,
  "model": "<string>",
  "provider": "<string>",
  "choices": [
    {
      "index": 123,
      "message": {
        "role": "system",
        "content": "<string>",
        "name": "<string>",
        "tool_calls": [
          {
            "id": "<string>",
            "type": "function",
            "function": {
              "name": "<string>",
              "arguments": "<string>",
              "description": "<string>",
              "parameters": {}
            }
          }
        ],
        "images": [
          {
            "type": "image_url",
            "image_url": {
              "url": "<string>"
            },
            "mime_type": "<string>"
          }
        ],
        "audios": [
          {
            "type": "audio_url",
            "audio_url": {
              "url": "<string>"
            },
            "mime_type": "<string>",
            "format": "wav"
          }
        ],
        "tool_call_id": "<string>"
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 123,
    "completion_tokens": 123,
    "total_tokens": 123,
    "server_tool_use": {
      "datetime_requests": 1,
      "web_search_requests": 1,
      "subagent_requests": 1,
      "fusion_requests": 1,
      "search_models_requests": 1,
      "web_fetch_requests": 1,
      "advisor_requests": 1,
      "image_generation_requests": 1,
      "apply_patch_requests": 1
    }
  }
}

Server tools

/v1/chat/completions supports regular function tools and these gateway-managed server tools:

gateway:datetime
phaseo:web_search
phaseo:web_fetch
phaseo:advisor
phaseo:image_generation

Datetime example

curl https://api.phaseo.app/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5-nano",
    "stream": false,
    "messages": [
      { "role": "user", "content": "What is the current datetime in Europe/London?" }
    ],
    "tools": [
      {
        "type": "gateway:datetime",
        "parameters": { "timezone": "Europe/London" }
      }
    ],
    "tool_choice": "auto"
  }'

When a server tool is used, usage includes:

{
  "usage": {
    "prompt_tokens": 12,
    "completion_tokens": 34,
    "total_tokens": 46,
    "server_tool_use": {
      "datetime_requests": 1
    }
  }
}

phaseo:web_search adds server_tool_use.web_search_requests, server_tool_use.web_search_results, and server_tool_use.web_search_extra_results. phaseo:web_fetch adds server_tool_use.web_fetch_requests.

Streaming note

stream: true is also supported. For gateway-managed server tools, Phaseo may materialize the upstream tool-call turn and re-emit a synthetic stream after continuing the loop.

Authorizations

Authorization

string

header

required

Bearer token authentication

Body

application/json

model

string

required

messages

object[]

required

Minimum array length: 1

Show child attributes

reasoning

object

Show child attributes

reasoning_effort

enum<string>

OpenAI-compatible alias for reasoning.effort.

Available options:

none,

minimal,

low,

medium,

high,

xhigh,

max

frequency_penalty

number

Required range: -2 <= x <= 2

logit_bias

object

Show child attributes

max_completion_tokens

integer

Required range: x >= 1

max_tokens

integer

Required range: x >= 1

metadata

object

Show child attributes

session_id

string

Unique identifier for grouping related requests (for example, a conversation or agent workflow) for observability.

Maximum string length: 256

presence_penalty

number

Required range: -2 <= x <= 2

seed

integer

Required range: -9223372036854776000 <= x <= 9223372036854776000

store

boolean

stream

boolean

default:false

stream_options

object

temperature

number

default:1

Required range: 0 <= x <= 2

tools

object[]

Tool definitions for model function calls and gateway server tools. Built-in server tools include datetime, web search, web fetch, Advisor, Subagent, Fusion, model search, image generation, and patch creation.

Show child attributes

max_tool_calls

integer

Required range: x >= 1

parallel_tool_calls

boolean

default:true

tool_choice

Tool selection strategy. Phaseo server-tool types are accepted and rewritten into upstream function/tool targets.

Available options:

auto,

none,

required,

phaseo:datetime,

phaseo:web_search,

phaseo:web_fetch,

phaseo:subagent,

phaseo:fusion,

phaseo:search_models,

gateway:datetime,

gateway:web_search,

gateway:web_fetch

logprobs

boolean

default:false

top_logprobs

integer

Required range: 0 <= x <= 20

top_p

number

Required range: 0 <= x <= 1

stop

response_format

modalities

enum<string>[]

Available options:

text,

image,

audio

image_config

object

Show child attributes

usage

boolean

provider

Provider selector. Use a string for a single provider, or routing options such as { "only": ["groq"] }.

Available options:

openai,

anthropic,

google-ai-studio,

gemini,

mistral,

x-ai,

xai,

groq,

together

provider_options

object

Optional provider-specific options.

Show child attributes

user_id

string

user

string

service_tier

enum<string>

Available options:

standard,

fast,

priority,

flex,

batch

prompt_cache_key

string | null

safety_identifier

string | null

Response

200 - application/json

Chat completion response

string

nativeResponseId

string | null

object

string

created

integer

model

string

provider

string

choices

object[]

Show child attributes

usage

object

Show child attributes

Last modified on July 26, 2026

API Guides

API Reference

Create a chat completion

Server tools

Datetime example

Streaming note

Authorizations

Body

Response

​Server tools

​Datetime example

​Streaming note

Authorizations

Body

Response

Server tools

Datetime example

Streaming note