2025-05-22
On May 22, Anthropic announced Claude 4. Alongside this, they also released a CLI tool called Claude Code. As I prefer interacting with computers via the terminal (shoutout to Ghostty), I was eager to try it out. For interacting with Claude models, I use the API. This document will record my impressions and experiences. Let's see how far I can go with just $5.
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claude --version
1.0.0 (Claude Code)
OK we are now ready to interact so let's start. Create a new empty folder change to it and ...
claude
✻ Welcome to Claude Code!
My first prompt was to create a Tetris game using pure JavaScript in a single HTML file. This way, we can simply open the file and start playing. In less than a minute, Tetris was created and playable. ✔
Now let's give another try and create an console app in pure js which get's a file and count the rows.
Input
Create a single-file JavaScript console app that counts and prints the number of rows in a given text using an emoji and the row count.
Output
● Created row-counter.js - a console app that counts text rows and displays them with emoji. Usage: node row-counter.js <filename> or pipe text to it.
> /cost
⎿ Total cost: $0.0298
Total duration (API): 31.7s
Total duration (wall): 1m 10.3s
Total code changes: 44 lines added, 0 lines removed
Token usage by model:
claude-3-5-haiku: 2.1k input, 150 output, 0 cache read, 0 cache write
claude-sonnet: 19 input, 590 output, 41.9k cache read, 1.6k cache write
Test
node row-counter.js row-counter.js
44 rows
Conclusion
As you see the model create a file with 44 lines 44 lines added. It cost ~ $0.02. Then we used the app to validate and we et here the same result 44 rows. So we checked if app is running and if lines matches.
Finally we also can let create the AI a CLAUDE.md file. Which is a kind of README.md generated by AI for AI und US.
Every step you take involves interacting with the model. It seems that Claude's code decides which model to use. For basic tasks, it uses "claude-3-5-haiku," which is cheaper compared to more advanced models.
You can check the cost of a session with a command, but even executing the cost command itself incurs a cost!
> /cost
⎿ Total cost: $0.1198
Total duration (API): 42s
Total duration (wall): 17m 34.8s
Total code changes: 33 lines added, 0 lines removed
Token usage by model:
claude-3-5-haiku: 1.8k input, 145 output, 0 cache read, 0 cache write
claude-sonnet: 40 input, 823 output, 118.9k cache read, 18.6k cache write
We saw previously that every interaction with the model costs. So it makes sense in near future we will think more in Mtok. Instead horse power HS or computing power Hertz we calculate using unity Mtok.
> /model
Switch between Claude models. Applies to this session and future Claude Code sessions. For custom model names, specify with --model.
1. Default (recommended) Use the default model (currently Claude Sonnet 4) · $3/$15 per Mtok
2. Opus Claude Opus 4 for complex tasks · $15/$75 per Mtok
So my hole experience (incl. Tetris game creation, create CLAUDE.md, run commands) cost ~ 0.25$. Now let's exit Claude Code with
:q