---
title: "MPP challenge with no usable intent — x402 defect class mpp-intent-unregistered-or-missing"
description: "MPP challenge with no usable intent (mpp-intent-unregistered-or-missing), an x402 defect class: The intent parameter is present and is either a drafted intent (charge, subscription) or one implementers advertise (session). Detectable by an unpaid probe. Without an intent a client cannot tell a one-off charge from a recurring commitment; a client that guesses charge on a subscription challenge signs for more than it meant to."
canonical: "https://scvd.store/defects/mpp-intent-unregistered-or-missing"
url: "https://scvd.store/defects/mpp-intent-unregistered-or-missing"
term_code: "mpp-intent-unregistered-or-missing"
defined_in: "https://scvd.store/defects"
data: "https://scvd.store/defects.json"
vocabulary_version: "22"
license: "https://creativecommons.org/licenses/by/4.0/"
---

# MPP challenge with no usable intent

`mpp-intent-unregistered-or-missing` — an x402 defect class.

**Asserts:** The intent parameter is present and is either a drafted intent (charge, subscription) or one implementers advertise (session).

**Costs:** Without an intent a client cannot tell a one-off charge from a recurring commitment; a client that guesses charge on a subscription challenge signs for more than it meant to.

**Detectable:** unpaid — a free probe can see it

**Falsified by:** The challenge naming a drafted or widely advertised intent at the stated moment.

**How an operator clears it:** Name the intent on every challenge; charge for a one-off, subscription for recurring; if you advertise session, know that it has no draft and a registry-only client cannot pay it.

**What a buyer does:** Do not sign against a challenge whose intent you do not recognise: you cannot know whether you are committing once or repeatedly. Refuse, and say which intent you could not read.

**Our signal:** `mpp-intent-registered`

---

Vocabulary v22, CC BY 4.0. Every class: https://scvd.store/defects. Machine-readable, with falsifiers and cross-instrument mappings: https://scvd.store/defects.json.

A class describes a property of one endpoint at one moment and never accumulates into a judgment on an operator.