OpenAI Agents SDK sandbox harness
Updated OpenAI Agents
Summary
On April 15, 2026, OpenAI's Agents SDK gained a sandbox-aware harness for files, commands, and long-running tasks. Python shipped first.
- Tool
- OpenAI Agents
- Category
- Frameworks
- Date
- Open source
- Yes
- Pricing
- Standard API pricing based on tokens and tool use. No separate SDK license fee is stated.
- Sources
On April 15, 2026, OpenAI published an update to the Agents SDK aimed at agents that inspect files, run commands, edit code, and work on long-horizon tasks inside a sandbox. The post describes configurable memory, sandbox-aware orchestration, Codex-like filesystem tools, and standardized integrations with primitives used in frontier agent systems.
Sandbox execution is native. A Manifest abstraction describes the workspace so the same agent can move across providers. Developers can mount local files, define output directories, and bring data from AWS S3, Google Cloud Storage, Azure Blob Storage, and Cloudflare R2.
The capabilities are generally available through the API at standard token and tool pricing. The harness and sandbox features launched first in Python, with TypeScript support described as planned. The post also says code mode and subagents were still in progress for both languages at the time of writing.
The September Agents API is the hosted follow-on. Both are on the OpenAI Agents hub.
Alternatives
| Tool | License | Pricing note |
|---|---|---|
OpenAI AgentsThis launchOpenAI's agent harness, shipped as a Python SDK update in April 2026 and as the hosted Agents API in September 2026. | Open source | SDK and Agents API use standard token and tool pricing. The Agents API has no additional fee. |
MastraTypeScript agent framework. Mastra Code is the terminal agent; AgentController is the extracted loop, in @mastra/core 1.47.0 or later. | Open source | Mastra Code and AgentController are announced as open source. No license fee is stated in the posts we cited. |
OpenHandsMIT-licensed project to build and run AI coding agents: start locally, automate workflows, use any model. | MIT | The OpenHands repository is MIT-licensed. Hosted plans are not priced on this page. |
More from OpenAI Agents
OpenAI Agents API
OpenAI AgentsOpenAI's Agents API, in public beta from September 10, 2026, exposes the Codex harness and an optional hosted sandbox.
Category: Agent infra
Pricing: Usage-based
Questions
What is the OpenAI Agents API?
Announced September 10, 2026, the Agents API is a public beta that exposes the harness behind Codex. OpenAI maintains the harness. There is no additional fee beyond tokens and tools. An optional hosted sandbox uses Codex's sandbox infrastructure.
What is the Agents SDK?
The April 15, 2026 SDK update adds sandbox-aware orchestration, filesystem tools, configurable memory, and a Manifest for mounting files from local disk or cloud storage. It launched in Python first.
What are alternatives to OpenAI Agents?
Mastra's AgentController is an open-source class in @mastra/core. OpenHands is a MIT-licensed workspace for running agents.
Filed on Agent Radar. Claims in this note are limited to the sources above.