Exploring the Mystery Behind Anthropic's "claude-3-7-sonnet-20250219" Model

Today, Anthropic launched the "claude-3-7-sonnet-20250219" model, and I was excited to put it to the test. I wrote a small script to experiment with it, but to my surprise, the model was never available. Instead, the model Claude used was either “Opus 3” or “Sonnet 3.5.” This was intriguing, as I was expecting "claude-3-7-sonnet-20250219."

I decided to investigate further. The first thing I did was review the API documentation on the Claude site and ensure that my code was aligned with the expected parameters. After confirming everything seemed correct, I ran the code in a loop to see what model Claude was actually using.

Running the Code Multiple Times

To be certain that there wasn’t an intermittent issue, I decided to run the code 500 times in a loop. I wanted to gather data on how often the model was using the "claude-3-7-sonnet-20250219" model and see if there was any pattern.

The results were clear:

• 481 times, the model used was "Sonnet 3.5"

• 19 times, it used "Opus 3"

This is the code I used to perform the test:

Checking the Logs

After seeing the results from the loop, I checked the logs on the Claude site for additional insights. The logs clearly indicated that I had been using the "claude-3-7-sonnet-20250219" model, but that wasn't reflected in the results.

What Am I Missing?

Despite everything looking right on my end and in the documentation, it seems something is off. My usage logs show that I’ve used the "claude-3-7-sonnet-20250219" model, but the output suggests otherwise. I’m left wondering: What am I missing?