> ## Documentation Index > Fetch the complete documentation index at: https://docs.viorant.ai/llms.txt > Use this file to discover all available pages before exploring further. # Agents > What an Agent is in Viorant, and how it's composed. An **Agent** is the runnable unit you build in Viorant. It's not a single thing you write — it's a **composition** of smaller, reusable parts: * a **Prompt** — the reasoning and instructions, * a **Model** — the provider and model it runs on, * zero or more **Skills** — the tasks it can perform, and * the **Tools** those skills use (built-in, or served by a **Connector**). You author each part in its own **Master** (a dedicated editor), then bring them together on the [Agent](/masters/agent) canvas to produce one agent you can run and test. ## Why composition Because the parts are separate and reusable, the same prompt, model config, or skill can back many agents — and each part is something you can read, version, and reason about on its own. The agent is the assembly; the Masters are where the real authoring happens. How the five authoring surfaces fit together.