400 Error on Vanilla use of function calling API?

[DGaffney]

Hello!

Just getting started here - I've created an API key via https://aistudio.google.com/app/apikey and done nothing else to configure - I have my API key from that site - and I run the code as follows (and API key is set correctly). The function calling example doesn't work, but the toy demo they provide does workj

client = Gemini.new(
  credentials: {
    service: 'generative-language-api',
    api_key: ENV['GOOGLE_API_KEY']
  },
  options: { model: 'gemini-pro', server_sent_events: true }
)
input = {
  tools: {
    function_declarations: [
      {
        name: 'date_and_time',
        description: 'Returns the current date and time in the ISO 8601 format for a given timezone.',
        parameters: {
          type: 'object',
          properties: {
            timezone: {
              type: 'string',
              description: 'A string represents the timezone to be used for providing a datetime, following the IANA (Internet Assigned Numbers Authority) Time Zone Database. Examples include "Asia/Tokyo" and "Europe/Paris". If not provided, the default timezone is the user\'s current timezone.'
            }
          }
        }
      }
    ]
  },
  contents: [
    { role: 'user', parts: { text: 'What time is it?' } }
  ]
}
irb(main):068:0> result = client.stream_generate_content(input)                                                                                                                                                                                                                                                                                                                                                                          
ETHON: performed EASY effective_url=https://generativelanguage.googleapis.com/v1/models/gemini-1.0-pro:streamGenerateContent?alt=sse&key=XXX response_code=400 return_code=ok total_time=0.038375                                                                                                                                                                                                    
/usr/local/lib/ruby/gems/3.1.0/gems/faraday-2.12.0/lib/faraday/response/raise_error.rb:30:in `on_complete': the server responded with status 400 (Faraday::BadRequestError)                                                                                                                                                                                                                                                              

The basic toy demo works fine:

irb(main):077:0> input = {"contents":[{"parts":[{"text":"Explain how AI works"}]}]}
=> {:contents=>[{:parts=>[{:text=>"Explain how AI works"}]}]}
irb(main):078:0> result = client.stream_generate_content(input)
ETHON: performed EASY effective_url=https://generativelanguage.googleapis.com/v1/models/vertex-ai-api:streamGenerateContent?key=XXX response_code=404 return_code=ok total_time=0.093008
/usr/local/lib/ruby/gems/3.1.0/gems/faraday-2.12.0/lib/faraday/response/raise_error.rb:30:in `on_complete': the server responded with status 404 (Faraday::ResourceNotFound)
irb(main):079:0> result
=> 
[{"candidates"=>                          
   [{"content"=>{"parts"=>[{"text"=>"**Artificial Intelligence (AI)** is the simulation of human intelligence processes by machines,"}], "role"=>"model"},
     "finishReason"=>"STOP",              
     "index"=>0,                          
     "safetyRatings"=>                    

I'm guessing I'm missing some configuration for my account - any leads on what the likely error is here?