Skillintermediate

Calling Finetuned Models

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Claude Code Knowledge Pack7/10/2026

Overview

Calling Finetuned Models

OpenAI

Model Name	Function Call
fine tuned `gpt-4-0613`	`response = completion(model="ft:gpt-4-0613", messages=messages)`
fine tuned `gpt-4o-2024-05-13`	`response = completion(model="ft:gpt-4o-2024-05-13", messages=messages)`
fine tuned `gpt-3.5-turbo-0125`	`response = completion(model="ft:gpt-3.5-turbo-0125", messages=messages)`
fine tuned `gpt-3.5-turbo-1106`	`response = completion(model="ft:gpt-3.5-turbo-1106", messages=messages)`
fine tuned `gpt-3.5-turbo-0613`	`response = completion(model="ft:gpt-3.5-turbo-0613", messages=messages)`

Vertex AI

Fine tuned models on vertex have a numerical model/endpoint id.

from litellm import completion

## set ENV variables
os.environ["VERTEXAI_PROJECT"] = "hardy-device-38811"
os.environ["VERTEXAI_LOCATION"] = "us-central1"

response = completion(
  model="vertex_ai/<your-finetuned-model>",  # e.g. vertex_ai/4965075652664360960
  messages=[{ "content": "Hello, how are you?","role": "user"}],
  base_model="vertex_ai/gemini-1.5-pro" # the base model - used for routing
)

Add Vertex Credentials to your env

!gcloud auth application-default login

Setup config.yaml

- model_name: finetuned-gemini
  litellm_params:
    model: vertex_ai/<ENDPOINT_ID>
    vertex_project: <PROJECT_ID>
    vertex_location: 
  model_info:
    base_model: vertex_ai/gemini-1.5-pro # IMPORTANT

Test it!

curl --location 'https://0.0.0.0:4000/v1/chat/completions' \\
--header 'Content-Type: application/json' \\
--header 'Authorization: <LITELLM_KEY>' \\
--data '{"model": "finetuned-gemini" ,"messages":[{"role": "user", "content":[{"type": "text", "text": "hi"}]}]}'