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

# Introduction

> SirenSpec is a YAML-first agent orchestration SDK for defining and running multi-agent workflows.

## What is SirenSpec?

SirenSpec lets you define multi-agent AI workflows in human-readable YAML and execute them against OpenAI, Anthropic, or Ollama backends. You describe *what* each agent does and *how* agents connect — SirenSpec handles the rest.

```yaml theme={null}
version: "0.1"

agents:
  assistant:
    model: "openai:gpt-4o-mini"
    system: "You are a helpful assistant. Answer questions clearly and concisely."

nodes:
  answer:
    agent: assistant
    writes: output.reply

input:
  message: "What is the capital of France?"
```

```bash theme={null}
sirenspec run workflow.yaml
# → { "output": { "reply": "Paris" }, ... }
```

## Key Features

<CardGroup cols={2}>
  <Card title="YAML Workflows" icon="file-code">
    Define agents, nodes, edges, and guardrails in a single readable YAML file.
  </Card>

  <Card title="Multiple Providers" icon="server">
    Works with OpenAI, Anthropic, and Ollama out of the box.
  </Card>

  <Card title="Guardrails" icon="shield">
    Built-in injection detection and output length limiting on every agent call.
  </Card>

  <Card title="CLI + SDK" icon="terminal">
    Run workflows from the command line or import directly into Python code.
  </Card>
</CardGroup>

## How It Works

1. **Define agents** — each agent has a model URI (`provider:model`) and a system prompt.
2. **Define nodes** — each node binds an agent to an output path in the workflow context.
3. **Connect nodes with edges** — edges control execution order and support conditional branching via `when:` expressions.
4. **Run** — SirenSpec executes nodes in topological order, routing outputs through the context, and returns a structured JSON trace.

## Next Steps

<CardGroup cols={2}>
  <Card title="Quickstart" icon="rocket" href="/quickstart">
    Install SirenSpec and run your first workflow in minutes.
  </Card>

  <Card title="YAML Reference" icon="book" href="/yaml-reference">
    Complete reference for all workflow fields and options.
  </Card>
</CardGroup>