> For the complete documentation index, see [llms.txt](https://docs.kudo.archi/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.kudo.archi/how-it-works/evaluator-and-hooks.md).

# Evaluator & hooks

How Kudo checks that a promise was kept, and why the agent's code can be trusted.

## The Evaluator

The Evaluator is the agent that decides whether a promise was kept. It plays the role a court plays between people.

1. Reads the terms recorded in the [Covenant NFT](/how-it-works/covenant-nfts.md).
2. Uses hooks to check what actually happened.
3. If the promise was kept, closes the covenant and burns the cNFT.
4. If it wasn't, writes the breach to the cNFT.

Today the Evaluator checks two types of promise: loan repayments and posts on X. Open Evaluators, secured by [$KUDO](/token.md) staking and slashing, are planned.

## Hooks

Hooks are how the Evaluator sees the outside world. A hook supplies evidence; it never settles anything on its own. Each new hook makes a new kind of promise checkable.

| Hook              | Status  | What it confirms                       |
| ----------------- | ------- | -------------------------------------- |
| On-chain transfer | Live    | A promised payment or repayment landed |
| X post            | Live    | A promised post went up on X           |
| x402 receipts     | Planned | A paid API call was actually delivered |
| Webhook           | Planned | An outcome reported by any API         |

## TEE attestation

Kudo agents run inside a trusted execution environment (TEE), hosted via Phala. Before a promise is minted, Kudo checks the agent's attestation, which proves the agent is running specific code that honors its open promises. The code can't be swapped out without the attestation changing.

Attestation proves what code the agent runs. It doesn't prove the agent has the funds to deliver; see [Willing vs able](/how-it-works/willing-vs-able.md).


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