> ## Documentation Index
> Fetch the complete documentation index at: https://docs.atlasyield.club/llms.txt
> Use this file to discover all available pages before exploring further.

# What the Engine does not do

> The boundaries that keep the Engine a proposal, never a custodian.

* **It never takes custody.** It proposes a portfolio; the user holds their own funds and
  signs every transaction.
* **It does not rebalance on its own.** Nothing moves without an explicit signature.
* **It makes no yield promise.** Expected return is an estimate from current rates and
  past variance, not a guarantee.
* **It never overrides the score.** It can only choose among vaults the scoring model
  already judged eligible.
* **It is not "AI".** There is no guessing model and no language model in the loop — it
  is deterministic optimization with the parameters published on the
  [tier policy page](/engine/tier-policy).