Lorenze/fix google vertex api using api keys (#4243)

* supporting vertex through api key use - expo mode

* docs update here

* docs translations

---------

Co-authored-by: Greyson LaLonde <greyson.r.lalonde@gmail.com>

lib/crewai/tests/cassettes/llms/google/test_google_express_mode_works.yaml

@@ -0,0 +1,75 @@
+interactions:
+- request:
+    body: '{"contents": [{"parts": [{"text": "\nCurrent Task: What is the capital
+      of Japan?\n\nThis is the expected criteria for your final answer: The capital
+      of Japan\nyou MUST return the actual complete content as the final answer, not
+      a summary.\n\nBegin! This is VERY important to you, use the tools available
+      and give your best Final Answer, your job depends on it!\n\nThought:"}], "role":
+      "user"}], "systemInstruction": {"parts": [{"text": "You are Research Assistant.
+      You are a helpful research assistant.\nYour personal goal is: Find information
+      about the capital of Japan\nTo give my best complete final answer to the task
+      respond using the exact following format:\n\nThought: I now can give a great
+      answer\nFinal Answer: Your final answer must be the great and the most complete
+      as possible, it must be outcome described.\n\nI MUST use these formats, my job
+      depends on it!"}], "role": "user"}, "generationConfig": {"stopSequences": ["\nObservation:"]}}'
+    headers:
+      User-Agent:
+      - X-USER-AGENT-XXX
+      accept:
+      - '*/*'
+      accept-encoding:
+      - ACCEPT-ENCODING-XXX
+      connection:
+      - keep-alive
+      content-length:
+      - '952'
+      content-type:
+      - application/json
+      host:
+      - aiplatform.googleapis.com
+      x-goog-api-client:
+      - google-genai-sdk/1.59.0 gl-python/3.13.3
+      x-goog-api-key:
+      - X-GOOG-API-KEY-XXX
+    method: POST
+    uri: https://aiplatform.googleapis.com/v1/publishers/google/models/gemini-2.0-flash-exp:generateContent
+  response:
+    body:
+      string: "{\n  \"candidates\": [\n    {\n      \"content\": {\n        \"role\":
+        \"model\",\n        \"parts\": [\n          {\n            \"text\": \"The
+        capital of Japan is Tokyo.\\nFinal Answer: Tokyo\\n\"\n          }\n        ]\n
+        \     },\n      \"finishReason\": \"STOP\",\n      \"avgLogprobs\": -0.017845841554495003\n
+        \   }\n  ],\n  \"usageMetadata\": {\n    \"promptTokenCount\": 163,\n    \"candidatesTokenCount\":
+        13,\n    \"totalTokenCount\": 176,\n    \"trafficType\": \"ON_DEMAND\",\n
+        \   \"promptTokensDetails\": [\n      {\n        \"modality\": \"TEXT\",\n
+        \       \"tokenCount\": 163\n      }\n    ],\n    \"candidatesTokensDetails\":
+        [\n      {\n        \"modality\": \"TEXT\",\n        \"tokenCount\": 13\n
+        \     }\n    ]\n  },\n  \"modelVersion\": \"gemini-2.0-flash-exp\",\n  \"createTime\":
+        \"2026-01-15T22:27:38.066749Z\",\n  \"responseId\": \"2mlpab2JBNOFidsPh5GigQs\"\n}\n"
+    headers:
+      Alt-Svc:
+      - h3=":443"; ma=2592000,h3-29=":443"; ma=2592000
+      Content-Type:
+      - application/json; charset=UTF-8
+      Date:
+      - Thu, 15 Jan 2026 22:27:38 GMT
+      Server:
+      - scaffolding on HTTPServer2
+      Transfer-Encoding:
+      - chunked
+      Vary:
+      - Origin
+      - X-Origin
+      - Referer
+      X-Content-Type-Options:
+      - X-CONTENT-TYPE-XXX
+      X-Frame-Options:
+      - X-FRAME-OPTIONS-XXX
+      X-XSS-Protection:
+      - '0'
+      content-length:
+      - '786'
+    status:
+      code: 200
+      message: OK
+version: 1

lib/crewai/tests/llms/google/test_google.py

@@ -728,3 +728,39 @@ def test_google_streaming_returns_usage_metrics():
     assert result.token_usage.prompt_tokens > 0
     assert result.token_usage.completion_tokens > 0
     assert result.token_usage.successful_requests >= 1
+
+
+@pytest.mark.vcr()
+def test_google_express_mode_works() -> None:
+    """
+    Test Google Vertex AI Express mode with API key authentication.
+    This tests Vertex AI Express mode (aiplatform.googleapis.com) with API key
+    authentication.
+
+    """
+    with patch.dict(os.environ, {"GOOGLE_GENAI_USE_VERTEXAI": "true"}):
+        agent = Agent(
+            role="Research Assistant",
+            goal="Find information about the capital of Japan",
+            backstory="You are a helpful research assistant.",
+            llm=LLM(
+                model="gemini/gemini-2.0-flash-exp",
+            ),
+            verbose=True,
+        )
+
+        task = Task(
+            description="What is the capital of Japan?",
+            expected_output="The capital of Japan",
+            agent=agent,
+        )
+
+
+        crew = Crew(agents=[agent], tasks=[task])
+        result = crew.kickoff()
+
+        assert result.token_usage is not None
+        assert result.token_usage.total_tokens > 0
+        assert result.token_usage.prompt_tokens > 0
+        assert result.token_usage.completion_tokens > 0
+        assert result.token_usage.successful_requests >= 1