What is the OpenAI Agents SDK?

1 min read Updated

The OpenAI Agents SDK is a lightweight, production-focused framework for building AI agents with built-in support for tool calling, agent handoffs, guardrails, and tracing — designed to work with OpenAI's models.

WHY IT MATTERS

OpenAI's Agents SDK (formerly Swarm) takes a minimalist approach to agent building. The core primitives are agents (with instructions and tools), handoffs (transferring control between agents), and guardrails (input/output validation). That's it.

This simplicity is intentional. Rather than providing abstractions for every possible pattern, the SDK gives you composable building blocks. Agents are just configurations — instructions, tools, and optional handoff targets. The runner handles the execution loop.

The SDK includes built-in tracing for observability, making it straightforward to debug agent behavior in production. For financial applications, the tracing capabilities provide the audit trail needed to understand why an agent made a particular decision.

HOW POLICYLAYER USES THIS

PolicyLayer works with the OpenAI Agents SDK by wrapping financial tools with policy checks. When an agent calls a payment tool, PolicyLayer validates the transaction before execution — adding spending controls to the SDK's lightweight agent loop.

FREQUENTLY ASKED QUESTIONS

How is the Agents SDK different from the Assistants API?
The Assistants API is a hosted, stateful solution managed by OpenAI. The Agents SDK is a client-side library you run yourself, giving you full control over execution, state, and tool implementation.
Can I use non-OpenAI models with the Agents SDK?
The SDK is designed for OpenAI models but supports any OpenAI-compatible API endpoint. This means providers offering OpenAI-compatible APIs can work, though function calling behavior may vary.
What are guardrails in the Agents SDK?
Guardrails are validation functions that check agent inputs and outputs. They can reject dangerous inputs (prompt injection defense) or validate outputs before they're returned. They run in parallel with the agent for efficiency.

FURTHER READING

Enforce policies on every tool call

Intercept is the open-source MCP proxy that enforces YAML policies on AI agent tool calls. No code changes needed.

npx -y @policylayer/intercept
github.com/policylayer/intercept →
// GET IN TOUCH

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