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Gemini Tools

POST /v1beta/models/{model}:generateContent
As of March 23, 2026, Crazyrouter production has verified that gemini-3-pro-preview can reliably trigger these Gemini-native tool capabilities:
  • codeExecution
  • googleSearch
  • urlContext
  • functionDeclarations
This page keeps only request patterns and response markers that were reproduced against production.

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Code Execution

The following request returned both executableCode and codeExecutionResult in production: 
curl "https://crazyrouter.com/v1beta/models/gemini-3-pro-preview:generateContent?key=YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "contents": [
      {
        "role": "user",
        "parts": [
          {"text": "Use code execution. Compute the sum of the first 20 prime numbers and state the result."}
        ]
      }
    ],
    "tools": [
      {
        "codeExecution": {}
      }
    ]
  }'
Observed response shape: 
{
  "candidates": [
    {
      "content": {
        "parts": [
          {
            "executableCode": {
              "language": "PYTHON",
              "code": "..."
            }
          },
          {
            "codeExecutionResult": {
              "outcome": "OUTCOME_OK",
              "output": "639\n"
            }
          },
          {
            "text": "The sum is 639."
          }
        ]
      }
    }
  ]
}
The following request returned groundingMetadata in production, confirming that Google Search was actually used: 
curl "https://crazyrouter.com/v1beta/models/gemini-3-pro-preview:generateContent?key=YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "contents": [
      {
        "role": "user",
        "parts": [
          {"text": "Use Google Search. What are two AI news items from March 2026?"}
        ]
      }
    ],
    "tools": [
      {
        "googleSearch": {}
      }
    ]
  }'
Current markers to check:
  • candidates[0].groundingMetadata
  • Normal text output in candidates[0].content.parts[*].text

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URL Context

The following request returned urlContextMetadata in production, along with groundingMetadata: 
curl "https://crazyrouter.com/v1beta/models/gemini-3-pro-preview:generateContent?key=YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "contents": [
      {
        "role": "user",
        "parts": [
          {"text": "Use URL context to summarize https://example.com/ in one sentence."}
        ]
      }
    ],
    "tools": [
      {
        "urlContext": {}
      }
    ]
  }'
Current markers to check:
  • candidates[0].urlContextMetadata
  • candidates[0].groundingMetadata

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Custom Function Calling

The following request returned functionCall in production: 
curl "https://crazyrouter.com/v1beta/models/gemini-3-pro-preview:generateContent?key=YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "contents": [
      {
        "role": "user",
        "parts": [
          {"text": "What is the weather in Beijing? Use the provided function."}
        ]
      }
    ],
    "tools": [
      {
        "functionDeclarations": [
          {
            "name": "get_weather",
            "description": "Get weather info for a city",
            "parameters": {
              "type": "object",
              "properties": {
                "city": {
                  "type": "string"
                }
              },
              "required": ["city"]
            }
          }
        ]
      }
    ]
  }'
Observed response shape: 
{
  "candidates": [
    {
      "content": {
        "parts": [
          {
            "functionCall": {
              "name": "get_weather",
              "args": {
                "city": "Beijing"
              }
            }
          }
        ]
      }
    }
  ]
}
To continue the tool loop, send the tool result back with Gemini-native functionResponse.