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

# Agent SDK

> Build custom agents that integrate with Friday's runtime and tool ecosystem.

Friday ships with [built-in agents](/core-concepts/agents) for common integrations (GitHub, Jira, Slack, etc.), but your business has unique APIs, workflows, and domain logic. The Agent SDK lets you wrap those into custom agents the platform can orchestrate alongside built-ins in [jobs](/core-concepts/jobs).

## How it works

Your agent runs as a Python subprocess managed by Friday. It communicates with the outside world through the host:

<CardGroup cols={2}>
  <Card title="LLM access" icon="brain" href="/sdk/guides/call-llms">
    Route calls through Friday's provider registry. No API keys in your code - the platform handles auth, rate limits, and routing.
  </Card>

  <Card title="HTTP requests" icon="globe" href="/sdk/guides/make-http-requests">
    Call external APIs through Friday's fetch layer. TLS termination and timeouts handled by Friday.
  </Card>

  <Card title="MCP tools" icon="wrench" href="/sdk/guides/use-mcp-tools">
    Configure Model Context Protocol servers and invoke tools - GitHub, databases, filesystems, and more.
  </Card>

  <Card title="Progress streaming" icon="bars-progress" href="/sdk/guides/stream-progress">
    Emit real-time progress updates that appear in the Studio UI while your agent runs.
  </Card>
</CardGroup>

The subprocess model keeps credentials out of your code. All I/O flows through Friday. The platform manages credentials, rate limits, and audit logging.

## Language SDKs

Define agents in code using the Agent SDK. Each SDK provides a consistent interface for building agents that integrate with Friday's runtime, tools, and orchestration layer.

<CardGroup cols={2}>
  <Card title="Python" icon="python" href="/sdk/python">
    Build agents in Python. Runtime Python package with NATS subprocess execution. Install additional pure-Python packages into the agent environment. Set up [IDE support](/sdk/python#development-setup) for autocomplete and type checking.
  </Card>
</CardGroup>

Python is available today and more languages are coming soon. Don't see your language? [Reach out](/contact) to request an SDK for a specific language.