What Hefty Can Do

Instruments are how Hefty interacts with your computer and the world around it. When Hefty decides it needs to run a command, open a website, or manage a file, it reaches for an instrument. You don't need to tell Hefty which one to use - it picks the right one based on what you asked for.

Why instruments and not tools? A tool acts on something - it changes it, moves it, breaks it apart. An instrument is more nuanced: it measures, translates, and channels intent with precision. A wrench turns a bolt; a caliper reads a dimension. Hefty's capabilities work the same way - they don't just execute, they observe, interpret, and adapt. That's the difference between brute-force automation and something that actually understands what it's doing.

Built-in Capabilities

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Run Commands
Execute shell commands just like you would in a terminal. Install packages, run build scripts, check git status, or use any CLI tool on your system.
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Web & APIs
Make HTTP requests to interact with APIs, download data, or check services. Open pages in your browser to show you results directly.
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Applications
Launch, list, and close applications on your system. Hefty can open your editor, check what's running, or stop a process.
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Screen & Clipboard
Take screenshots to see what's on your display. Copy text to the clipboard. Hefty can "see" your screen and work with visual information.
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Analysis
Summarize long documents, extract structured data from text, and search through your conversation history for past context.
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Ask You
When Hefty needs clarification, it asks. Request your input, ask for confirmation before sensitive actions, or let you choose between options.
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Knowledge
Learn new skills from structured text, recall data about known entities, and manage secrets securely for use in API calls.
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System
Read environment variables and access system configuration. Hefty can check your setup and adapt its approach accordingly.

How Hefty Picks the Right Instrument

You don't need to know instrument names. When you send a message, Hefty's cognition pipeline figures out which instruments are needed, then the reasoning phase decides exactly what to call and with what parameters. If something fails, Hefty sees the error and tries a different approach.

Over time, Hefty learns from how it uses its instruments - which approaches work well for specific situations and which to avoid - so it gets better the more you use it.

Safety

Every instrument has a risk level so Hefty understands the impact of what it's about to do:

  • Read-only - just looking, no changes
  • Local write - modifies files on your machine
  • System execute - runs commands in your terminal
  • Network - makes external requests
  • Critical - high-impact operations

Hefty factors risk into its planning and shows the risk level alongside each action in the UI, so you always know what's happening.

Extending Hefty

Hefty ships with a full set of built-in instruments, but you can add more:

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MCP Connections
Connect to external MCP servers and their capabilities become available as instruments instantly. This is how you integrate Hefty with other AI ecosystems.
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Custom Prompts
Define specialized AI tasks as reusable instruments - like a code reviewer that applies your team's checklist to any code snippet.
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API Endpoints
Point Hefty at any HTTP API and it becomes a callable instrument. Define the URL, method, and parameters - Hefty handles the rest.
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Plugins
Install third-party instrument packages. Plugins can be added, enabled, or removed without restarting Hefty.

All extensions persist across restarts and can be managed from the Hefty UI.