> ## Documentation Index
> Fetch the complete documentation index at: https://docs.usefused.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Folder-owned SubAgents

> Give a SubAgent its own instructions, tools, MCP connections, skills, and sandbox.

A folder SubAgent is a separate composition boundary.

```text theme={null}
subagents/researcher/
├── agent.py
├── instructions.md
├── tools/
├── mcp/
├── skills/
├── sandbox/
└── subagents/       ADK-only recursive discovery
```

## Ownership properties

| Resource             | Child can own it? | Inherited from parent? |
| -------------------- | ----------------: | ---------------------: |
| `instructions.md`    |               Yes |                     No |
| `tools/`             |               Yes |                     No |
| `mcp/`               |               Yes |                     No |
| `skills/`            |               Yes |                     No |
| `sandbox/`           |               Yes |                     No |
| `plugins/`           |                No |                     No |
| `extensions/`        |                No |             Root-owned |
| `models/` and `lib/` |                No |         Root namespace |

The child's private capabilities are not exposed to the parent merely because the directory is nested.

## Discovery rules

| Rule                                               | Result                        |
| -------------------------------------------------- | ----------------------------- |
| `agent.py` export matches the folder name          | Stable SubAgent identity      |
| Supported child folders are discovered by location | No manual capability list     |
| Unsupported root-only folder is populated          | Compilation fails             |
| Parent references the child                        | Harnest wires the composition |

<Card title="Framework behavior" icon="code-branch" href="/harnest/build/subagents/framework-behavior">
  Check recursive discovery and portable graph behavior before choosing the layout.
</Card>