Gemini Generating Content - CometAPI Documentation

POST

v1beta

models

{model}

{operator}

import os
from google import genai

client = genai.Client(
    api_key=os.environ["COMETAPI_KEY"],
    http_options={"api_version": "v1beta", "base_url": "https://api.cometapi.com"},
)

response = client.models.generate_content(
    model="gemini-3-flash-preview",
    contents="Explain how AI works in a few words",
)

print(response.text)

{
  "candidates": [
    {
      "content": {
        "role": "<string>",
        "parts": [
          {
            "text": "<string>",
            "functionCall": {
              "name": "<string>",
              "args": {}
            },
            "inlineData": {
              "mimeType": "<string>",
              "data": "<string>"
            },
            "thought": true
          }
        ]
      },
      "safetyRatings": [
        {
          "category": "<string>",
          "probability": "<string>",
          "blocked": true
        }
      ],
      "citationMetadata": {
        "citationSources": [
          {
            "startIndex": 123,
            "endIndex": 123,
            "uri": "<string>",
            "license": "<string>"
          }
        ]
      },
      "tokenCount": 123,
      "avgLogprobs": 123,
      "groundingMetadata": {
        "groundingChunks": [
          {
            "web": {
              "uri": "<string>",
              "title": "<string>"
            }
          }
        ],
        "groundingSupports": [
          {
            "groundingChunkIndices": [
              123
            ],
            "confidenceScores": [
              123
            ],
            "segment": {
              "startIndex": 123,
              "endIndex": 123,
              "text": "<string>"
            }
          }
        ],
        "webSearchQueries": [
          "<string>"
        ]
      },
      "index": 123
    }
  ],
  "promptFeedback": {
    "safetyRatings": [
      {
        "category": "<string>",
        "probability": "<string>",
        "blocked": true
      }
    ]
  },
  "usageMetadata": {
    "promptTokenCount": 123,
    "candidatesTokenCount": 123,
    "totalTokenCount": 123,
    "trafficType": "<string>",
    "thoughtsTokenCount": 123,
    "promptTokensDetails": [
      {
        "modality": "<string>",
        "tokenCount": 123
      }
    ],
    "candidatesTokensDetails": [
      {
        "modality": "<string>",
        "tokenCount": 123
      }
    ]
  },
  "modelVersion": "<string>",
  "createTime": "<string>",
  "responseId": "<string>"
}

CometAPI supports the Gemini native API format, giving you full access to Gemini-specific features like thinking control, Google Search grounding, native image generation modalities, and more. Use this endpoint when you need capabilities not available through the OpenAI-compatible chat endpoint.

Both x-goog-api-key and Authorization: Bearer headers are supported for authentication.

Quick start

To use any Gemini SDK or HTTP client with CometAPI, replace the base URL and API key:

Setting	Google Default	CometAPI
Base URL	`generativelanguage.googleapis.com`	`api.cometapi.com`
API key	`$GEMINI_API_KEY`	`$COMETAPI_KEY`

Send video input

Gemini generateContent accepts video as a content part. Choose the input shape based on where the video is stored:

Video source	Request part	Use when
Local video file	`inlineData`	The video is small enough to send as base64 in the JSON request.
Public video URL	`fileData.fileUri`	The video is available through a public HTTPS URL that does not require authentication.

For REST and curl requests, use Gemini’s camelCase field names such as inlineData.mimeType and fileData.fileUri. Do not send URL media as file_data.file_uri.

This example reads a local MP4 file, encodes it as base64, and sends it in the request body:

read -rsp "CometAPI API key: " COMETAPI_KEY
printf '\n'
export COMETAPI_KEY
VIDEO_PATH="./your_video.mp4"
VIDEO_B64=$(base64 < "$VIDEO_PATH" | tr -d '\n')

curl -X POST \
  "https://api.cometapi.com/v1beta/models/gemini-3.5-flash:generateContent" \
  -H "Content-Type: application/json" \
  -H "x-goog-api-key: $COMETAPI_KEY" \
  --data-binary @- <<EOF
{
  "contents": [
    {
      "role": "user",
      "parts": [
        {
          "inlineData": {
            "mimeType": "video/mp4",
            "data": "${VIDEO_B64}"
          }
        },
        {
          "text": "Analyze this video and list the key scenes."
        }
      ]
    }
  ],
  "generationConfig": {
    "maxOutputTokens": 512,
    "thinkingConfig": {"thinkingLevel": "MINIMAL"}
  }
}
EOF

This example sends a public MP4 URL with fileData.fileUri:

read -rsp "CometAPI API key: " COMETAPI_KEY
printf '\n'
export COMETAPI_KEY
VIDEO_URL="https://interactive-examples.mdn.mozilla.net/media/cc0-videos/flower.mp4"

curl -X POST \
  "https://api.cometapi.com/v1beta/models/gemini-3.5-flash:generateContent" \
  -H "Content-Type: application/json" \
  -H "x-goog-api-key: $COMETAPI_KEY" \
  --data-binary @- <<EOF
{
  "contents": [
    {
      "role": "user",
      "parts": [
        {
          "fileData": {
            "mimeType": "video/mp4",
            "fileUri": "${VIDEO_URL}"
          }
        },
        {
          "text": "Analyze this video and list the key scenes."
        }
      ]
    }
  ],
  "generationConfig": {
    "maxOutputTokens": 512,
    "thinkingConfig": {"thinkingLevel": "MINIMAL"}
  }
}
EOF

CometAPI does not recommend a separate Gemini Files API upload flow for this endpoint. Send media in the generateContent request itself with inlineData or fileData.fileUri.

Configure thinking (reasoning)

Gemini models can perform internal reasoning before generating a response. The control method depends on the model generation.

Gemini 3 (thinkingLevel)
Gemini 2.5 (thinkingBudget)

Gemini 3 models use thinkingLevel to control reasoning depth. Available levels: MINIMAL, LOW, MEDIUM, HIGH.Use gemini-3-flash-preview as the default example model unless you specifically need a different Gemini 3 variant.

curl "https://api.cometapi.com/v1beta/models/gemini-3-flash-preview:generateContent" \
  -H "Content-Type: application/json" \
  -H "x-goog-api-key: $COMETAPI_KEY" \
  -d '{
    "contents": [{"parts": [{"text": "Explain quantum physics simply."}]}],
    "generationConfig": {
      "thinkingConfig": {"thinkingLevel": "LOW"}
    }
  }'

Gemini 2.5 models use thinkingBudget for fine-grained token-level control:

0 — disable thinking
-1 — dynamic (model decides, default)
> 0 — specific token budget (e.g., 1024, 2048)

curl "https://api.cometapi.com/v1beta/models/gemini-2.5-flash:generateContent" \
  -H "Content-Type: application/json" \
  -H "x-goog-api-key: $COMETAPI_KEY" \
  -d '{
    "contents": [{"parts": [{"text": "Solve this logic puzzle step by step."}]}],
    "generationConfig": {
      "thinkingConfig": {"thinkingBudget": 2048}
    }
  }'

Using thinkingLevel with Gemini 2.5 models (or thinkingBudget with Gemini 3 models) may cause errors. Use the correct parameter for your model version.

Stream responses

To receive Server-Sent Events as the model generates content, use streamGenerateContent?alt=sse as the operator. Each SSE event contains a data: line with a JSON GenerateContentResponse object.

curl "https://api.cometapi.com/v1beta/models/gemini-3-flash-preview:streamGenerateContent?alt=sse" \
  -H "Content-Type: application/json" \
  -H "x-goog-api-key: $COMETAPI_KEY" \
  --no-buffer \
  -d '{
    "contents": [{"parts": [{"text": "Write a short poem about the stars"}]}]
  }'

Set system instructions

To guide the model’s behavior across the entire conversation, use systemInstruction:

curl "https://api.cometapi.com/v1beta/models/gemini-3-flash-preview:generateContent" \
  -H "Content-Type: application/json" \
  -H "x-goog-api-key: $COMETAPI_KEY" \
  -d '{
    "contents": [{"parts": [{"text": "What is 2+2?"}]}],
    "systemInstruction": {
      "parts": [{"text": "You are a math tutor. Always show your work."}]
    }
  }'

Request JSON output

To force structured JSON output, set responseMimeType. Optionally provide a responseSchema for strict schema validation:

curl "https://api.cometapi.com/v1beta/models/gemini-3-flash-preview:generateContent" \
  -H "Content-Type: application/json" \
  -H "x-goog-api-key: $COMETAPI_KEY" \
  -d '{
    "contents": [{"parts": [{"text": "List 3 planets with their distances from the sun"}]}],
    "generationConfig": {
      "responseMimeType": "application/json"
    }
  }'

Ground with Google Search

To enable real-time web search, add a googleSearch tool:

curl "https://api.cometapi.com/v1beta/models/gemini-3-flash-preview:generateContent" \
  -H "Content-Type: application/json" \
  -H "x-goog-api-key: $COMETAPI_KEY" \
  -d '{
    "contents": [{"parts": [{"text": "Who won the euro 2024?"}]}],
    "tools": [{"google_search": {}}]
  }'

The response includes groundingMetadata with source URLs and confidence scores.

Response example

A typical response from CometAPI’s Gemini endpoint:

{
  "candidates": [
    {
      "content": {
        "role": "model",
        "parts": [{"text": "Hello"}]
      },
      "finishReason": "STOP",
      "avgLogprobs": -0.0023
    }
  ],
  "usageMetadata": {
    "promptTokenCount": 5,
    "candidatesTokenCount": 1,
    "totalTokenCount": 30,
    "trafficType": "ON_DEMAND",
    "thoughtsTokenCount": 24,
    "promptTokensDetails": [{"modality": "TEXT", "tokenCount": 5}],
    "candidatesTokensDetails": [{"modality": "TEXT", "tokenCount": 1}]
  },
  "modelVersion": "gemini-3-flash-preview",
  "createTime": "2026-03-25T04:21:43.756483Z",
  "responseId": "CeynaY3LDtvG4_UP0qaCuQY"
}

The thoughtsTokenCount field in usageMetadata shows how many tokens the model spent on internal reasoning, even when thinking output is not included in the response.

Compare with OpenAI-compatible endpoint

Feature	Gemini Native (`/v1beta/models/...`)	OpenAI-Compatible (`/v1/chat/completions`)
Thinking control	`thinkingConfig` with `thinkingLevel` / `thinkingBudget`	Not available
Google Search grounding	`tools: [\{"google_search": \{\}\}]`	Not available
Google Maps grounding	`tools: [\{"googleMaps": \{\}\}]`	Not available
Image generation modality	`responseModalities: ["IMAGE"]`	Not available
Auth header	`x-goog-api-key` or `Bearer`	`Bearer` only
Response format	Gemini native (`candidates`, `parts`)	OpenAI format (`choices`, `message`)

Authorizations

x-goog-api-key

string

header

required

Your CometAPI key passed via the x-goog-api-key header. Bearer token authentication (Authorization: Bearer $COMETAPI_KEY) is also supported.

Path Parameters

model

string

required

Gemini model ID. Example: gemini-3-flash-preview, gemini-2.5-pro. See the Models page for current options.

operator

enum<string>

required

The operation to perform. Use generateContent for synchronous responses, or streamGenerateContent?alt=sse for Server-Sent Events streaming.

Available options:

generateContent,

streamGenerateContent?alt=sse

Body

application/json

contents

object[]

Conversation content. Each entry has an optional role (user or model) and a parts array.

Show child attributes

systemInstruction

object

System instructions that guide the model's behavior across the entire conversation. Text only.

Show child attributes

tools

object[]

Tools the model may use to generate responses. Supports function declarations, Google Search, Google Maps, and code execution.

Show child attributes

toolConfig

object

Configuration for tool usage, such as function calling mode.

Show child attributes

safetySettings

object[]

Safety filter settings. Override default thresholds for specific harm categories.

Show child attributes

generationConfig

object

Configuration for model generation behavior including temperature, output length, and response format.

Show child attributes

cachedContent

string

The name of cached content to use as context. Format: cachedContents/{id}. See the Gemini context caching documentation for details.

Response

200 - application/json

Successful response. For streaming requests, the response is a stream of SSE events, each containing a GenerateContentResponse JSON object prefixed with data:.

candidates

object[]

The generated response candidates.

Show child attributes

promptFeedback

object

Feedback on the prompt, including safety blocking information.

Show child attributes

usageMetadata

object

Token usage statistics for the request.

Show child attributes

modelVersion

string

The model version that generated this response.

createTime

string

The timestamp when this response was created (ISO 8601 format).

responseId

string

Unique identifier for this response.

Anthropic Messages

Which image models can I use with CometAPI?

import os
from google import genai

client = genai.Client(
    api_key=os.environ["COMETAPI_KEY"],
    http_options={"api_version": "v1beta", "base_url": "https://api.cometapi.com"},
)

response = client.models.generate_content(
    model="gemini-3-flash-preview",
    contents="Explain how AI works in a few words",
)

print(response.text)

{
  "candidates": [
    {
      "content": {
        "role": "<string>",
        "parts": [
          {
            "text": "<string>",
            "functionCall": {
              "name": "<string>",
              "args": {}
            },
            "inlineData": {
              "mimeType": "<string>",
              "data": "<string>"
            },
            "thought": true
          }
        ]
      },
      "safetyRatings": [
        {
          "category": "<string>",
          "probability": "<string>",
          "blocked": true
        }
      ],
      "citationMetadata": {
        "citationSources": [
          {
            "startIndex": 123,
            "endIndex": 123,
            "uri": "<string>",
            "license": "<string>"
          }
        ]
      },
      "tokenCount": 123,
      "avgLogprobs": 123,
      "groundingMetadata": {
        "groundingChunks": [
          {
            "web": {
              "uri": "<string>",
              "title": "<string>"
            }
          }
        ],
        "groundingSupports": [
          {
            "groundingChunkIndices": [
              123
            ],
            "confidenceScores": [
              123
            ],
            "segment": {
              "startIndex": 123,
              "endIndex": 123,
              "text": "<string>"
            }
          }
        ],
        "webSearchQueries": [
          "<string>"
        ]
      },
      "index": 123
    }
  ],
  "promptFeedback": {
    "safetyRatings": [
      {
        "category": "<string>",
        "probability": "<string>",
        "blocked": true
      }
    ]
  },
  "usageMetadata": {
    "promptTokenCount": 123,
    "candidatesTokenCount": 123,
    "totalTokenCount": 123,
    "trafficType": "<string>",
    "thoughtsTokenCount": 123,
    "promptTokensDetails": [
      {
        "modality": "<string>",
        "tokenCount": 123
      }
    ],
    "candidatesTokensDetails": [
      {
        "modality": "<string>",
        "tokenCount": 123
      }
    ]
  },
  "modelVersion": "<string>",
  "createTime": "<string>",
  "responseId": "<string>"
}

​Quick start

​Send video input

​Configure thinking (reasoning)

​Stream responses

​Set system instructions

​Request JSON output

​Ground with Google Search

​Response example

​Compare with OpenAI-compatible endpoint

Authorizations

Path Parameters

Body

Response

Quick start

Send video input

Configure thinking (reasoning)

Stream responses

Set system instructions

Request JSON output

Ground with Google Search

Response example

Compare with OpenAI-compatible endpoint