> For the complete documentation index, see [llms.txt](/llms.txt).
> A full single-fetch corpus is available at [llms-full.txt](/llms-full.txt).
---
title: Build with AGNT5
description: Define workflows, functions, agents, prompts, webhooks, and approval steps before you deploy.
last_verified: 2026-06-30
---

Build is where you define the application code AGNT5 runs. A **[workflow](/docs/build/workflows.md)** is a durable program made of checkpointed steps, an **[agent](/docs/build/agents.md)** is a reasoning loop that can call tools, and a **[function](/docs/build/functions.md)** wraps deterministic work with retries and trace visibility. Use these pages when you are shaping behavior locally before creating a **[deployment](/docs/run/deploying.md)**.

## Build guides


  - [Functions](/docs/build/functions) — Wrap deterministic work in retryable, observable units.
  - [Workflows](/docs/build/workflows) — Compose multi-step programs with durable state and checkpointed execution.
  - [Agents](/docs/build/agents) — Define reasoning loops that call tools and keep state across a run.
  - [Tools](/docs/build/tools) — Expose capabilities an agent can call during its loop.
  - [Sandboxes](/docs/build/sandboxes) — Attach isolated file and code execution workspaces to agents.
  - [Skills](/docs/build/skills) — Load capabilities on demand with SKILL.md folders instead of bloating the prompt.
  - [Prompts](/docs/build/prompts) — Keep prompt text versioned and runnable from code.
  - [Prompt caching](/docs/build/prompt-caching) — Reuse stable prompt prefixes across model calls to cut latency and token spend.
  - [Human in the Loop](/docs/build/human-in-the-loop) — Pause a workflow until a person approves or supplies input.
  - [Webhooks](/docs/build/webhooks) — Receive external events and route them into AGNT5 workflows.
  - [Model Context Protocol](/docs/build/mcp) — Import external MCP tools or expose AGNT5 primitives to MCP clients.
  - [Local development](/docs/build/local-development) — Run your project with agnt5 dev and trigger it from Studio, the CLI, or the API.


Outcome: you have local code that defines the workflow behavior, model calls, external inputs, and approval points AGNT5 will run.

## Next steps



After you understand the Build section, start with the path that matches your current project.

- [Run locally](/docs/build/local-development): Start the worker with `agnt5 dev` and trigger runs from Studio.
- [Define a workflow](/docs/build/workflows): Compose durable steps and checkpointed execution.
- [Deploy the code](/docs/run/deploying): Move the worker into an AGNT5 environment.