> ## Documentation Index > Fetch the complete documentation index at: https://docs.vatel.ai/llms.txt > Use this file to discover all available pages before exploring further. # Function Nodes > Nodes in the agent editor that become tools A **function node** is a node in the [Agent Editor](/configure/agent-editor) that performs an action: integrations (e.g. email, CRM), API calls, or other external behavior. When you add a function node to the conversation flow, it is automatically turned into a **tool** the agent can call. The agent sees the tool’s name, description, and parameters; you can preview that in the editor. This walkthrough uses a simple graph: a first message, a conversation, and a Resend email node. The email node becomes a tool named **Book meeting**. ## Step 1: Build the graph Start with a minimal conversation flow and add the integration node. 1. Add a **First message** node (e.g. welcome and ask how you can help). 2. Connect a **Conversation** node for the main dialogue. 3. Add a **Resend email** integration node after the conversation (e.g. to send a meeting confirmation). The graph looks like: **First message → Conversation → Resend email node**. Example graph: First message, Conversation, Resend email node ## Step 2: Name the tool (Book meeting) Configure the Resend email node with the sender, recipients, subject, and body. Set the node’s **name** (or tool label) to **Book meeting**. That name is what the agent sees as the tool name, e.g. `book_meeting` or "Book meeting", so the agent can offer to book a meeting and then call this tool to send the email. Resend email node configured as Book meeting ## Step 3: Preview the tool in the Agent Editor Every function node in the conversation graph becomes a tool. In the Agent Editor you can **preview** the tools generated from your graph. That preview shows exactly what the agent sees: tool name (e.g. Book meeting), description, and parameters. Use it to confirm the agent has the right capability and to tune names and descriptions for better behavior. Tool preview: Book meeting in the agent editor Once the graph is saved and the agent is published, the **Book meeting** tool is available during the conversation: the agent can invoke it when the user wants to book a meeting, and the Resend email node runs to send the confirmation.