Documentation · Explainer

ERC-8004 Validation Registry explained: how third-party validation of an agent works

ERC-8004 defines three registries. Identity says who an agent is, reputation collects open feedback, and the ValidationRegistry is meant to hold independent checks of specific work. This page covers what the draft says a validation request and response contain, who may call what, how it differs from reputation, and what a buyer can and cannot conclude today. ERC-8004 is still a draft, so details may change. Current ecosystem figures are on the stats page.

What the ValidationRegistry is

The ERC-8004 draft describes a ValidationRegistry alongside the IdentityRegistry (who an agent is) and the ReputationRegistry (what others have said). Its job is to let an agent ask a named third party, a validator, to check something specific, such as that a task was done correctly, and to leave a public record of the answer. It is a record-keeping contract: it stores the request and the response. It does not run the check and it does not decide whether the validator is any good.

The request / response flow

  1. Request. The agent's owner or operator calls validationRequest with the validator's address, the agentId, a requestURI pointing to what should be checked, and a requestHash that identifies the request.
  2. Response. The named validator calls validationResponse with the requestHash, a response value from 0 to 100, an optional responseURI and responseHash for the evidence, and an optional tag.
  3. Read. Anyone can read the status of a request by its hash, list the requests for an agent or for a validator, and read a summary (count and average response) filtered by validator addresses and tag.

The 0 to 100 value can be used as a simple pass/fail or as a spread. The draft allows a validator to respond more than once to the same request, for example an early answer followed by a final one, so read the latest response and its timestamp. Incentives and penalties for validators are outside the registry; each validation scheme handles its own.

Who can call what

  • validationRequest must come from the owner or an approved operator of the agent. A third party cannot open a validation about an agent that did not ask for it.
  • validationResponse must come from the validator address named in that request. Nobody else can answer it.
  • Reads are open to everyone.

This is the key difference from open feedback: the agent chooses the validator, and only that validator can respond.

Validation versus reputation

ReputationRegistryValidationRegistry
Who writesAny address except the agent's owner or operatorOnly the validator the agent named
About whatThe agent in general, optionally one endpointOne specific request
Main weaknessOpen posting, so one actor can look like many ratersThe agent picks its own validator, so the validator's independence has to be checked
Evidence linkOptional feedback URI and hashOptional response URI and hash

Neither one replaces testing the agent. See can you trust an ERC-8004 reputation score? for the reputation side.

Kinds of validator the draft mentions

The draft names several ways a validator might reach its answer: stake-backed re-execution of the agent's work (re-running it with money at stake), zero-knowledge proofs of the agent's output (cryptographic proofs), and attestations from trusted execution environments (secure hardware, or TEEs). A validator address can be a wallet or a contract. The registry treats them all the same, which is why the identity and method of a validator are part of what a buyer needs to read, not an implementation detail.

What a buyer can conclude

  1. Who is the validator? Is it independent of the agent, or an address the agent's owner controls? A response from a validator the agent controls proves little.
  2. What was asked? Open the request URI and check the hash. A high score on a narrow request says nothing about other behaviour.
  3. Is there evidence? Does the response carry a URI and a matching hash you can open?
  4. Is it current? Look at the timestamp and whether a later response replaced an earlier one.
  5. No validations is the normal case. Absence is not a bad sign; it means there is nothing to read.
  6. Still test the agent. Whether its endpoint responds and returns a payment challenge is checked on verify before paying.

Limits

Details follow the draft text as last read and may change.

FAQ

What is the ERC-8004 ValidationRegistry?

The third registry in the ERC-8004 draft. It is meant to record requests for an independent party (a validator) to check an agent's work or claims, and the validator's response as a number from 0 to 100 with an optional link to evidence.

Who can call validationRequest and validationResponse?

In the draft, validationRequest must be called by the owner or an approved operator of the agent, naming the validator. validationResponse must be called by that named validator, and may be called more than once for the same request.

Is the ValidationRegistry live and used?

We do not index validation records, so this page does not claim the ValidationRegistry is live or used. The IdentityRegistry and ReputationRegistry are the registries we index today.

How is validation different from reputation?

Reputation is open feedback from any address. Validation is a response from a validator the agent itself chose for one specific request. It is more targeted, but the agent picks the validator, so who the validator is matters as much as the score.