> ## Documentation Index
> Fetch the complete documentation index at: https://docs.phinite.ai/llms.txt
> Use this file to discover all available pages before exploring further.
# Attach RAG collections to nodes
> Ground Master and Child Agent nodes in workspace collections with threshold and top k.
In Graph Studio, agent nodes retrieve from **collections**, not from individual uploaded files. Open the node drawer **RAG** tab to attach collections and tune retrieval.
## Attach a collection
1. Open the **Agent Graph** in Graph Studio.
2. Select a **Master Agent** or **Child Agent** node (double-click if the drawer is closed).
3. Open the **RAG** tab.
4. Click **Attach collection**.
5. Select one or more workspace collections, then confirm.
6. Click **Save** on the Studio toolbar.
Attached collections show under **Knowledge** with a **rag** badge and on the node card as a folder label.
The drawer copy reads **Ground answers in your collections** — the agent retrieves relevant chunks before responding, not only what the model already knows.
## Threshold and top k
On the **RAG** tab, set retrieval controls for the node:
| Control | Meaning | Defaults (product) |
| ------------- | ------------------------------------ | -------------------------- |
| **Threshold** | Similarity floor for returned chunks | `0.20` |
| **Top k** | Maximum chunks retrieved per query | `3` (range typically 1–20) |
Raise **top k** when answers need broader context; raise **threshold** when you want only strong matches. Changes persist on the node when you commit the sliders/steppers — still **Save** the graph before **Build**.
## Detach or view
* Use **View** on a collection row to open collection details.
* Remove a collection from the node when it should no longer ground that agent.
* Manage sources and chunking on **BUILD → RAG Collections** ([connectors](/rag/connectors)).
## Related
Workspace collections and chunking.
Agent node drawers: Details, RAG, Tools, Variables.