Summary
KNX Association is pausing the registration and validation of new ETS Apps that act as MCP (Model Context Protocol) servers, effective immediately and until further notice. During the pause, we will not accept new MCP App registrations or first-time validation requests for such apps. We will announce the end of the pause in this article.
What MCP Apps for ETS are
An MCP App is an ETS App that runs a Model Context Protocol server inside ETS. It lets an external AI assistant or agent read, and in some cases change, the open ETS project and program devices.
ETS Apps are built with the ETS SDK and must pass ETS App validation before they are published in the KNX Online Shop. The SDK is meant to be used inside ETS, by validated code only. An MCP server, by design, opens that SDK functionality to software outside ETS that KNX Association has never validated.
Why we are pausing
We are pausing because MCP Apps, as they are built today, cannot be validated reliably against the App validation rules, and we want to treat every developer the same way.
- MCP opens the SDK outside ETS. The ETS SDK is meant to be used inside ETS by validated code. An MCP server passes SDK functions on to an external AI client. What that client sends to ETS is outside the scope of any App validation.
- Rule violations were found in published apps. A recent technical review of published MCP Apps found violations that the automatic validation did not report. Examples include starting external processes (rule 3), using internal ETS types that are not part of the SDK (rule 5), executable files inside the .etsapp container, and code that is encrypted so that it cannot be reviewed.
- Project data and device safety. Some apps send project content to external servers, accept commands from outside ETS, or program devices without a confirmation in ETS. Users cannot easily see this behaviour.
- Fair and equal treatment. Developers have asked for exceptions to the rules, for example to include an executable or to open network ports. Granting such exceptions case by case is not fair to developers who follow the rules. The rules must apply equally to all apps.
- Request volume. We receive new requests for MCP and AI-based apps almost every week. We need to update our rules and validation process for this kind of app before we accept more.
In parallel, we are working on an official, standardised way to connect AI tools to ETS, in which KNX Association controls which functions are offered.
What this means for you
| Situation | What happens during the pause |
|---|---|
| You plan to register a new MCP App | We do not accept the registration in MyKNX. Please wait for the end of the pause. |
| Your new MCP App is waiting for validation | Your request is on hold. We will contact you when the pause ends. |
| Your MCP App is already published | It stays available for now. We are reviewing all apps in the KNX Online Shop against the validation rules and will contact you if changes are needed. |
| You submit an update for a published MCP App | It is validated against the published rules. No exceptions are granted for executables or external processes. |
| You develop an ETS App that is not an MCP App | Nothing changes. Registration and validation continue as usual. |
| You use an MCP App in ETS | Installed apps keep working. Check in the app's documentation which data it sends and where, and keep a backup of your project before letting an AI tool change it. |
As stated in the validation rules, a validation can be revoked if a rule violation is found after validation.
Next steps and help
We will update this article when the review of published apps is finished and the updated rules for MCP Apps are defined. For questions about a specific app, submit a request in the Help Centre and select the ETS Apps topic.
Related articles: App validation rules · App validation process