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

# Build

> Playbooks, workflows, steps, tools and the two prompt layers: every part an agent is assembled from, and when to reach for each one.

| Term                                                    | What it is                                                                                                                                                      |
| ------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **[Playbook](/documentation/build/playbooks)**          | Agentic. Instructions driving toward a goal, calling tools as needed. Use for open-ended work: booking, qualifying, handling a return.                          |
| **[Workflow](/documentation/build/workflows)**          | Deterministic. Steps drawn on a canvas from the Start chip. Use where the path must be fixed: authentication, IVR menus, scripted onboarding.                   |
| **Step**                                                | One node on a workflow canvas. Named with only the first word capitalised: Message step, API step, Function step.                                               |
| **[Tool](/documentation/build/tools/overview)**         | Something a playbook can call mid-conversation: functions, API tools, MCP tools, integrations, and the built-in system tools.                                   |
| **Function**                                            | Custom JavaScript that runs in Voiceflow's sandbox and returns through a named path.                                                                            |
| **API tool**                                            | A saved HTTP request an agent can make.                                                                                                                         |
| **[Global prompt](/documentation/build/global-prompt)** | The always-on layer shaping identity, tone and guardrails on every turn.                                                                                        |
| **[Instructions](/documentation/build/instructions)**   | The routing layer: which playbook or workflow handles what.                                                                                                     |
| **Trigger**                                             | What tells the agent when a playbook or workflow applies. Older material calls this the "LLM Description"; the current name is Trigger.                         |
| **[Behaviour](/documentation/build/behaviour)**         | The model, voice and memory settings an agent runs under.                                                                                                       |
| **Function path**                                       | One of the named exits a function can return through. Paths are what let a function branch rather than just return a value.                                     |
| **Function variable**                                   | An input or output a function declares. Inputs are passed in when it runs; outputs are written back for later steps to read.                                    |
| **API tool variable**                                   | An input an API tool substitutes into its request, so one saved request can serve many calls.                                                                   |
| **API step**                                            | Makes an HTTP request from inside a workflow, at a fixed point in the path rather than when a model decides to.                                                 |
| **Buttons**                                             | Presents a fixed set of choices instead of open input, so the next turn is one of a known few.                                                                  |
| **Call forward**                                        | Transfers a live voice call to another number.                                                                                                                  |
| **Card**                                                | One rich message: an image, a title, a description and optional buttons.                                                                                        |
| **Carousel**                                            | Several cards the user can browse through in one turn.                                                                                                          |
| **Code**                                                | Runs JavaScript inline at one point in a workflow. A function is the reusable form of the same idea.                                                            |
| **Condition**                                           | Branches a workflow on a rule you write. The Operator step is the model-driven alternative.                                                                     |
| **Crew**                                                | Groups several playbooks so they hand off to each other inside one step, rather than routing through a separate agent. Lower latency than routing out and back. |
| **End**                                                 | Ends the conversation.                                                                                                                                          |
| **Integration**                                         | Calls a third-party service such as Salesforce, Shopify or Zendesk.                                                                                             |
| **Listen**                                              | Waits for the user to say or type something before continuing.                                                                                                  |
| **Live agent handoff**                                  | Hands the conversation to a human.                                                                                                                              |
| **Message**                                             | Says something to the user.                                                                                                                                     |
| **Operator**                                            | A silent, model-driven branch. Evaluates conditions in natural language and routes accordingly, producing no output the user sees.                              |
| **Set**                                                 | Assigns a value to a variable.                                                                                                                                  |
| **Agent tools**                                         | The tools attached to the agent itself rather than to one playbook.                                                                                             |
| **Function tool**                                       | A function exposed to a playbook as something it can call.                                                                                                      |
| **Global tools**                                        | APIs, integrations, MCP servers and functions added at the agent level, so every playbook can use them without adding each one individually.                    |
| **System tools**                                        | Native capabilities built into Voiceflow that need no setup: knowledge base search, web search, buttons, cards, end and call forward. Enabled by a toggle.      |