MCP for mobile apps.

Give your Android app agentic powers.

Apps describe what they can do. AI Assistant (Hark) discovers and invokes those capabilities. On-device. Open protocol.

Try It Out Add OACP to Your App View on GitHub

Hark means "to listen." It's also short for my name "Harkirat".

Start in the right place

Protocol

OACP

The open standard. Apps ship oacp.json. Assistants discover via ContentProvider.

Read the protocol →

Open-source assistant

Hark

Open-source voice assistant. On-device AI with EmbeddingGemma + Qwen3. Wake word, overlay UI, async results.

Meet Hark →

Android SDK

SDK

Easily add OACP to any Android app with these SDKs.

Get the SDK →

How it works

1
Describe the app
The app ships oacp.json and OACP.md so an assistant can understand the actions, parameters, and vocabulary.
2
Discover capabilities
An OACP-compatible assistant scans the device for .oacp ContentProviders and reads each manifest at runtime.
3
Match the request
The assistant uses its on-device pipeline to match the user's request to the best capability and extract any parameters.
4
Invoke the app
The assistant dispatches an Android intent. Background tasks use broadcasts and UI flows use activities.
5
Return the result
If the action is async, the app sends a structured result back and the assistant can speak or display it.

Background action (round trip)

 "Hey Hark, what's the weather?"
        │
        ▼
 ┌─────────────┐  broadcast   ┌─────────────────┐
 │    Hark     │─────────────►│  Weather App    │
 │  on-device  │   (OACP)     │                 │
 │     AI      │◄─────────────│  fetches data   │
 └─────────────┘ ACTION_RESULT└─────────────────┘
        │        
        ▼
 "Currently 22°, partly cloudy"

Foreground action (one way)

 "Hey Hark, take a picture with
  front camera in 2 seconds"
        │
        ▼
 ┌─────────────┐   (OACP)     ┌─────────────────┐
 │    Hark     │─────────────►│  Camera App     │
 │  on-device  │  activity    │                 │
 │     AI      │              │  opens camera,  │
 └─────────────┘              │  2s countdown   │
                              └─────────────────┘

Ecosystem

8 apps and counting. Breezy Weather, Binary Eye, Wikipedia, and more. Each one ships an oacp.json and works with any OACP assistant out of the box.

See all apps

What's next

Wake word detection is shipped. Background listening, self-hosted inference, and disambiguation UI are next. Everything is open source.

See the full roadmap