Lowfat – pluggable CLI filter that saved 91.8% of my LLM tokens

Hi HN,

Not sure if anyone would be interested.

But, just wanted to share that I've been maintaining my small tool called 'lowfat' that helps me filters some of my verbose CLI output.

It's a single binary, works as an agent hook or a shell wrapper. It has a plugin system to customize filters per command.

The idea is pretty simple: agents don't need the full kubectl get -o yaml or any 10k-line dump to make decisions. So that lowfat sits in between, strips the noise, and passes through what matters.

Here's my real report after 2 months of personal use:

lowfat history --all

  lowfat plugin candidates
  ─────────────────────────────────────────────────────────
#  command                    runs   avg raw      cost   savings  source    status  
1  kubectl get                101x     14.4K      1.5M     93.9%  plugin    good    
2  grep                       103x     13.5K      1.4M     96.2%  plugin    good    
3  git diff                    81x       995     80.6K     57.9%  built-in  good    
4  kubectl                     90x       485     43.6K     33.6%  plugin    good    
5  docker                     127x      5.5K    693.6K     96.1%  built-in  good    
6  ls                         489x       117     57.3K     56.2%  built-in  good    
7  find                        30x     16.5K    495.0K     95.5%  plugin    good    
8  git show                    63x       490     30.9K     38.0%  built-in  good    
9  git                        177x       368     65.2K     76.1%  built-in  good    
10 git log 86x 556 47.8K 78.5% built-in good
11 kubectl logs 5x 3.6K 17.8K 43.0% plugin good
12 git status 86x 152 13.1K 58.0% built-in good
13 docker ps 20x 467 9.3K 52.8% plugin good
14 kubectl describe 6x 656 3.9K 1.2% plugin weak
15 docker images 9x 940 8.5K 61.8% built-in good
16 k get 2x 2.1K 4.2K 35.9% plugin good
17 terraform 10x 395 3.9K 32.1% plugin good
18 git commit 32x 77 2.5K 0.0% built-in weak
19 docker build 8x 487 3.9K 37.6% built-in good
20 docker compose 22x 979 21.5K 89.4% built-in good
total: 4.4M raw → 4.1M saved (91.8%)

My toolset above is kind limited, but it works pretty well for my usecase without any interruption Kinda help me not reaching the token limit for my company Bedrock limit usage and keep optimizing the saving on the go for later usage.

But, why not alternatives (https://github.com/zdk/lowfat#alternatives) ? The answers are:

• My goal is to make the core lightweight but extensible via plugins i.e. not trying to bundle every command in the installed binary so that people own their output filters.
• Customizable per usecase via plugin or filter pipelines as I am using my own toolset.
• Customizable for non-public CLI tools, for example, some enterprise might have their interal CLI tools that public won't have access.
• People should own their data. So the design is local-first, No telemetry forever.
• I kinda love UNIX-style composible pipes, so lowfat-filter has implemented this style.
• Be able to adjust aggressiveness of the filter, so we can control that we won't strip something the agent needed.

  GitHub: https://github.com/zdk/lowfat

  Anyway, if anyone is interested, feedbacks and questions are welcome!

  Thanks!