I Had Fable 5 Build My Perfect Second Brain (and why you should too)

It mapped 35,466 files, and cut my retrieval costs by 40%

What if finding any file in your workspace cost your agent 40% fewer tokens?

That's what I got when Claude Fable 5 built me a proper second brain. The same lookups that used to take 50k tokens now take 30k, and the answer comes back faster 💪🏻

I walk through how I guided Fable to build this system here:

The framework underneath is four layers - your Applications, Routines, Memory, and Skills. Get those four right and you're ahead of 99% of people using AI agents.

To have Fable build the same for you, point it at these:

- QMD (by Toby L, Shopify founder). Brings semantic search to your notes, so it matches on meaning, not just exact words.

- Gbrain (Garry Tan, YC CEO). The second-brain setup he runs himself - a clean reference pattern to copy.

- Graphify (YC-funded). Builds smarter connections between your files and folders.

- /last30days (Matt Van Horn, Lyft co-founder). A skill that scours Reddit, X, YouTube and Hacker News for what's actually working right now.

If you want Fable to build one for your setup - I've made a full guide for your agent that you can get here for free

— Jay

P.S: Remember that it's less than 24 hours 'til Fable 5 stops being part of your claude subscription, so build away!