OpenAI Agents SDK (Python)

Use this skill when developing AI agents using OpenAI Agents SDK (openai-agents package).

Quick Reference

Installation

uv add openai-agents        # or `pip install openai-agents` outside a uv project

Environment Variables

OPENAI_API_KEY=sk-...

Using Azure or another provider instead? See agents.md — don't hardcode provider env vars here, they vary and go stale.

Basic Agent

from agents import Agent, Runner

agent = Agent(
    name="Assistant",
    instructions="You are a helpful assistant.",
    model="gpt-5.6-sol",  # or "gpt-5.6-terra" / "gpt-5.6-luna" (cheaper tiers).
                          # "gpt-5.6" is an alias for gpt-5.6-sol. Verify
                          # current IDs from the model catalog.
)

# Synchronous
result = Runner.run_sync(agent, "Tell me a joke")
print(result.final_output)

# Asynchronous
result = await Runner.run(agent, "Tell me a joke")

Omitting model= uses the SDK's built-in default (currently gpt-5.6-luna with low-effort reasoning settings) — set it explicitly in production so an upstream default change cannot swap tiers silently.

Key Patterns

Pattern	Purpose
Basic Agent	Simple Q&A with instructions
Azure/LiteLLM	Azure OpenAI integration
AgentOutputSchema	Strict JSON validation with Pydantic
Function Tools	External actions (@function_tool)
Streaming	Real-time UI (Runner.run_streamed)
Handoffs	Specialized agents, delegation
Agents as Tools	Orchestration (agent.as_tool)
LLM as Judge	Iterative improvement loop
Guardrails	Input/output validation
Sessions	Automatic conversation history
Multi-Agent Pipeline	Multi-step workflows
Sandboxing	SandboxAgent — filesystem, shell and skills inside a local/Docker sandbox (beta)
Tracing	Built-in spans for runs, tools, handoffs and guardrails; pluggable processors

The SDK has no separate Subagent class: express delegation with handoffs or agent.as_tool(). For model-written tool orchestration, use ProgrammaticToolCallingTool and verify its Responses-only constraints.

Preferred: Live Docs via MCP

Model names and API details change frequently. When available, consult the OpenAI Developer Docs MCP server (openaiDeveloperDocs) before relying on the static references below.

Setup (Codex CLI):

codex mcp add openaiDeveloperDocs --url https://developers.openai.com/mcp

Setup (Claude Code):

claude mcp add --transport http openaiDeveloperDocs https://developers.openai.com/mcp

Or config (~/.codex/config.toml, VS Code .vscode/mcp.json, Cursor ~/.cursor/mcp.json):

[mcp_servers.openaiDeveloperDocs]
url = "https://developers.openai.com/mcp"

Key tools: mcp__openaiDeveloperDocs__search_openai_docs, fetch_openai_doc, list_api_endpoints, get_openapi_spec.

Rules: Cite fetched docs. Never speculate on field names, defaults, or current model IDs — fetch first. Keep quotes under 125 chars.

Fallback when MCP is unavailable: https://developers.openai.com/api/docs/llms.txt (plain-text index of all API docs; each entry has a .md twin at /api/docs/<slug>.md).

Reference Documentation

Offline/quick-lookup snippets. Verify model names and API signatures against the MCP or docs when accuracy matters.

• agents.md - read when choosing or wiring a model: default-model caveat, LiteLLM, native Azure client
• tools.md - read when adding function tools, hosted tools, or agents-as-tools
• structured-output.md - read when the output must be a Pydantic/dataclass shape (AgentOutputSchema, strict vs non-strict)
• streaming.md - read when streaming to a UI (event types, SSE with FastAPI)
• handoffs.md - read when one agent delegates to another (handoff vs as_tool, input filters)
• guardrails.md - read when validating input/output or gating tool calls
• sessions.md - read when conversation history must persist across requests (SQLite, SQLAlchemy, Redis, OpenAI Conversations)
• patterns.md - read for multi-agent pipelines, LLM-as-judge loops, tracing controls, max_turns, parallelization
• sandbox.md - read when the agent must edit files or run commands in an isolated workspace (SandboxAgent, beta)

Official Documentation

• Docs: https://openai.github.io/openai-agents-python/
• Examples: https://github.com/openai/openai-agents-python/tree/main/examples
• Major update: https://openai.com/index/the-next-evolution-of-the-agents-sdk/
• Docs MCP setup: https://developers.openai.com/learn/docs-mcp
• Docs index (llms.txt): https://developers.openai.com/api/docs/llms.txt
• Current model IDs: https://platform.openai.com/docs/models