Is it possible to create a Hierarchical crew manager using Gemini and without LangChain?

CrewAI Community Support
3

You may have to set the planning_llm manually. Give this a try (replace the settings with your model/config):

Crew(
...
planning_llm=LLM(
  model="gemini/gemini-1.5-pro-002",
  api_key=GEMINI_API_KEY,
  temperature=0,
)
)

CrewAI docs has the planning_llm set up slightly different in their example, using the ChatOpenAI class langchain_openai for their LLM.
Source: Planning - CrewAI
If the first option doesn’t work, another idea would be to try a modified version of the doc example, instead using the ChatGoogleGenerativeAI class from langchain_google_genai. Note that you may need to add API keys/required values as necessary into this class.

Source:
ChatGoogleGenerativeAI — 🦜🔗 LangChain documentation.

Example:

from langchain_google_genai import ChatGoogleGenerativeAI
...
...
Crew(
    ...
    planning_llm=ChatGoogleGenerativeAI(model="gemini-1.5-pro")
)