Responses API

OpenAI partner models on Gemini Enterprise Agent Platform support the OpenAI Responses API (publishers/openai/v1/responses) for text generation from text and image inputs, tool calling, reasoning effort control, and conversation compaction.

Before you begin

To use OpenAI partner models with Gemini Enterprise Agent Platform, you must complete the following steps. The Gemini Enterprise Agent Platform API (aiplatform.googleapis.com) must be enabled on your Google Cloud project.

Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.

In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

Roles required to select or create a project

Select a project: Selecting a project doesn't require a specific IAM role—you can select any project that you've been granted a role on.
Create a project: To create a project, you need the Project Creator role (roles/resourcemanager.projectCreator), which contains the resourcemanager.projects.create permission. Learn how to grant roles.

Go to project selector

Verify that billing is enabled for your Google Cloud project.

Enable the Gemini Enterprise Agent Platform API, if it is not already enabled.

Roles required to enable APIs

To enable APIs, you need the serviceusage.services.enable permission. If you created the project, then you likely already have this permission through the Owner role (roles/owner). Otherwise, you can get this permission through the Service Usage Admin role (roles/serviceusage.serviceUsageAdmin). Learn how to grant roles.

Enable the API

In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

Roles required to select or create a project

Select a project: Selecting a project doesn't require a specific IAM role—you can select any project that you've been granted a role on.
Create a project: To create a project, you need the Project Creator role (roles/resourcemanager.projectCreator), which contains the resourcemanager.projects.create permission. Learn how to grant roles.

Go to project selector

Verify that billing is enabled for your Google Cloud project.

Enable the Gemini Enterprise Agent Platform API, if it is not already enabled.

Roles required to enable APIs

Enable the API

Complete the onboarding steps in OpenAI GPT Models, including purchasing the product through Google Cloud Marketplace and enabling the model in Model Garden.
If your organization's policy restricts model access, allow the model in that policy.

Required roles

To get the permissions that you need to call OpenAI partner models, ask your administrator to grant you the Agent Platform User (roles/aiplatform.user) IAM role on the project. For more information about granting roles, see Manage access to projects, folders, and organizations.

You might also be able to get the required permissions through custom roles or other predefined roles.

Endpoints

OpenAI partner models are served from the following Agent Platform base URLs:

Global endpoint (global): https://aiplatform.googleapis.com/v1/projects/PROJECT_ID/locations/global/publishers/openai/v1
US multi-region endpoint (us): https://aiplatform.us.rep.googleapis.com/v1/projects/PROJECT_ID/locations/us/publishers/openai/v1

Replace <var>PROJECT_ID</var> with your Google Cloud project ID.

Call the Responses API using the OpenAI Python SDK

You can use the official openai Python library by setting base_url to your Agent Platform endpoint and passing a refreshed Google Cloud OAuth 2.0 access token as api_key. Set store=False for stateless requests and ZDR workloads.

import google.auth
from google.auth.transport.requests import Request
from openai import OpenAI

credentials, _ = google.auth.default(
    scopes=["https://www.googleapis.com/auth/cloud-platform"]
)
credentials.refresh(Request())

project_id = "PROJECT_ID"
base_url = (
    f"https://aiplatform.googleapis.com/v1/projects/{project_id}"
    "/locations/global/publishers/openai/v1"
)

client = OpenAI(
    base_url=base_url,
    api_key=credentials.token,
)

response = client.responses.create(
    model="gpt-6.1-sol",
    input="Explain how Zero Data Retention works on Agent Platform.",
    reasoning={"effort": "medium"},
    store=False,
)
print(response.output_text)

Stream responses

To stream incremental text deltas over server-sent events (SSE), set stream=True:

import google.auth
from google.auth.transport.requests import Request
from openai import OpenAI

credentials, _ = google.auth.default(
    scopes=["https://www.googleapis.com/auth/cloud-platform"]
)
credentials.refresh(Request())

project_id = "PROJECT_ID"
base_url = (
    f"https://aiplatform.googleapis.com/v1/projects/{project_id}"
    "/locations/global/publishers/openai/v1"
)

client = OpenAI(
    base_url=base_url,
    api_key=credentials.token,
)

stream = client.responses.create(
    model="gpt-6-luna",
    input="Write a short Python function to validate a JSON schema.",
    stream=True,
    store=False,
)

for event in stream:
    if event.type == "response.output_text.delta":
        print(event.delta, end="")

Compact conversation history

For long-horizon agentic sessions, call the standalone compaction endpoint (POST .../responses/compact) to compress prior messages into an encrypted compaction item that can be passed into subsequent stateless /responses calls:

import google.auth
from google.auth.transport.requests import Request
from openai import OpenAI

credentials, _ = google.auth.default(
    scopes=["https://www.googleapis.com/auth/cloud-platform"]
)
credentials.refresh(Request())

project_id = "PROJECT_ID"
base_url = (
    f"https://aiplatform.googleapis.com/v1/projects/{project_id}"
    "/locations/global/publishers/openai/v1"
)

client = OpenAI(
    base_url=base_url,
    api_key=credentials.token,
)

compacted = client.responses.compact(
    model="gpt-6-astra",
    input=[
        {"role": "user", "content": "Audit our multi-region VPC firewall rules."},
        {"role": "assistant", "content": "I checked the ingress rules for us-east1 and us-central1."},
    ],
)
print(compacted.output)

Call the Responses API using the OpenAI Node.js SDK

You can use the official openai Node.js library with Google Cloud OAuth credentials:

import OpenAI from "openai";

const projectId = "PROJECT_ID";
const client = new OpenAI({
  apiKey: process.env.GOOGLE_CLOUD_ACCESS_TOKEN,
  baseURL: `https://aiplatform.googleapis.com/v1/projects/${projectId}/locations/global/publishers/openai/v1`,
});

const response = await client.responses.create({
  model: "gpt-6-luna",
  input: "Write a short summary of how authentication works on Agent Platform.",
  store: false,
});
console.log(response.output_text);

Call the Responses API using the OpenAI Go SDK

You can use the official openai-go library with Google Cloud OAuth credentials:

package main

import (
    "context"
    "fmt"
    "os"

    "github.com/openai/openai-go/v3"
    "github.com/openai/openai-go/v3/option"
    "github.com/openai/openai-go/v3/responses"
)

func main() {
    ctx := context.Background()
    projectID := "PROJECT_ID"
    client := openai.NewClient(
        option.WithAPIKey(os.Getenv("GOOGLE_CLOUD_ACCESS_TOKEN")),
        option.WithBaseURL("https://aiplatform.googleapis.com/v1/projects/"+projectID+"/locations/global/publishers/openai/v1"),
    )

    response, err := client.Responses.New(ctx, responses.ResponseNewParams{
        Model: "gpt-6-luna",
        Input: responses.ResponseNewParamsInputUnion{
            OfString: openai.String("Write a one-sentence bedtime story about a unicorn."),
        },
        Store: openai.Bool(false),
    })
    if err != nil {
        panic(err)
    }
    fmt.Println(response.OutputText())
}

Call the Responses API using curl

You can send a REST request directly to the Responses API using curl.

Before using any of the request data, make the following replacements:

PROJECT_ID: Your Google Cloud project ID.

HTTP method and URL:

POST https://aiplatform.googleapis.com/v1/projects/PROJECT_ID/locations/global/publishers/openai/v1/responses

Request JSON body:

{
  "model": "gpt-6.1-sol",
  "input": "Summarize the key differences between Google Cloud and OpenAI terms.",
  "reasoning": {"effort": "medium"},
  "store": false
}

To send your request, expand one of these options:

curl (Linux, macOS, or Cloud Shell)

Save the request body in a file named request.json, and execute the following command:

curl -X POST \
     -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
     -H "Content-Type: application/json; charset=utf-8" \
     -d @request.json \
     "https://aiplatform.googleapis.com/v1/projects/PROJECT_ID/locations/global/publishers/openai/v1/responses"

PowerShell (Windows)