OpenAI Agents API

14 hours ago (developers.openai.com)

I think we’re still figuring out the right abstraction for offering agents as a product.

- LLMs are a great foundation but building your own harness is a huge undertaking, a deep rabbit hole.

- There are harnesses available as open source libraries but that’s still coupled to an environment. Where does the state persist? Like maybe I’m a Cloudflare worker and don’t even have a file system.

Agent as a service like this lets you plug in the tools it needs to be whatever kind of agent you want. But they still get to encapsulate and continue to iterate on the really deep parts of the harness that all agents need like memory and context management.

That said, my money right now is not on the offerings from OpenAI and Anthropic because they’re stuck using their own proprietary frontier models and those aren’t actually the best choice for most agents right now. A competitor who is not an LLM lab gets their pick of the market at any given moment. Like you’d want to be using GLM 5.3 Flash right now for most things agentic.

  • > building your own harness is a huge undertaking, a deep rabbit hole.

    I eventually gave up on this task. It's not possible to fight OpenAI or Anthropic's engineering teams. Their reasoning models have all kinds of undocumented back door access to the base models that you'd never be able to replicate from the outside. Even if you had full access you would not have the engineering man hours or experience to keep up.

    I think this Agents API thing is a step too far, but Chat Completion is too cold now. Something approximating Responses API seems like the happy medium. You still get most of the control with the only blackbox part being the reasoning loop / tokens. Building agents using the GPT5.6 family w/ Responses API feels pretty close to Star Trek computer shit to me. I thought I was being clever with my DIY contraption on top of chat completion, but it wasn't even close. I have embraced the reality that I will need to use opaque reasoning tokens to give my clients the experiences they are paying me to provide.

    • I built my harness in pi within herdr, I cloned (zipped and downloaded) 0xRichardH/pi-herdr-subagents and went from there, and used pi to build itself, adding gate workflow state control, provider fallbacks (I use many token plans), subagent skill injection, etc.

      It is highly custom to my needs and wants, and I think every developer needs to do this. I only talk to my planner which plans, and it subs out to designer, oracle, coders, testers, and reviewers, etc. It is thus highly optimized for correctness. You can TDD or no TDD. You can fast track small changes. I tweak my harness dozens of times as I encounter new edge cases (esp when I switch models and encounter models not as good at following instructions).

      As you can start to see, it is better to own the harness because nobody can build something custom that 100% fits your needs or development philosophy.

      10 replies →

    • After being burned by the rug-pull of OpenAI retiring the Assistants API in favor of Responses last year, I swore off using heavily stateful APIs for language model access. I could be totally wrong, but at this point I'm more willing to use a proprietary harness headless than to abstract it into an API.

      1 reply →

    • I feel like you could use an open-source harness like Pi and get 100+% of what these closed APIs offer without getting locked to OpenAI. What do you think is missing from them?

      1 reply →

    • > > building your own harness is a huge undertaking, a deep rabbit hole. > I eventually gave up on this task.

      It's not trivial, but cmon, i did during weekends from my phone and FOR ME it's so much better than the codex or claude, it has every i need and want :D

      I'm using my own harness for work and hobby, has github integration, review mode, interactive voice mode, overlayed worktree, browser integration, mcp and much more.

      Using claude and codex feels like picking up a club, in-line with the caveman skill...

    • I've been working on a custom managed agent (see my other top-level comment), I find it is actually a manageable undertaking. It does feel herculean, but somehow doable. I do not find their hidden reasoning tokens to be insurmountable as long as you match the behavior of codex or CC (which takes work, but, again, is doable). My managed agent harness currently matches Codex on several benchmarks like Terminal Bench.

  • I think the abstraction is only part of the problem. The other part is that all these companies offering ai products are deeply untrustworthy, and I don’t want to let them any further into my stack than I have to. Claude code and codex are great because they are lightweight, and operate on top of the rest of my tools with little to no change needed, so they can be eliminated or migrated away from with zero cost. They’re not a dependency of anything. And that’s as much as I’m willing to trust OpenAI or Claude.

  • Been using bedrock agent core and seems to work fine for me. Although there might be a better abstraction.

  • > LLMs are a great foundation but building your own harness is a huge undertaking, a deep rabbit hole

    I’ve been doing this for the past few months. I started with a server where I ran pi in tmux and then used that to build an LLM gateway and agent session manager, then built deterministic workflows using bash scripts and a skill/script distribution system. The app works on desktop, mobile and web and it works great. Non technical colleagues are using it to build and ship real software and it’s cheap AF even using API pricing because it works well with Luna or deepseek.

    • I also use Luna and DeepSeek in a custom harness. (Mine is very minimal.) GLM also works great.

      I had issues with some other models but it seems to do with the system prompt and tool calling format. Some models seem to only work well with some harnesses.

      1 reply →

    • This is the "i made a voice controlled agent" thread all over again. lol, I too have made a stable of harnesses and tools to run them and have different levels of them monitoring each other and different spends to code/review/triage.

  • There might not be a good abstraction. I've built a few harnesses for different types of workflows, and the details are so different I struggle to see a good abstraction. It's also not clear there should be - if you look at most complex software systems, it's a collection of smaller abstractions/tools/systems pulled together to achieve X.

  • IMO building a harness is not wildly difficult (customize pi?) but the offerings from openai and anthropic are wildly subsidized in the subscriptions so they win by default if you want frontier capabilities. Glm 5.3 flash is great but it's not cheaper than a codex or Claude code 200 dollar sub and it does not have astra or fable level capabilities.

  • > you’d want to be using GLM 5.3 Flash right now for most things agentic

    That was yesterday. I think the crown currently belongs to DeepSeek Flash v4.1 for the next few days or weeks.

  • I just have a slack bot running on a VM that sees a message and invokes pi.

    It would be trivial for every request to clone a full lxd container and have all the tools and repos required if I wanted to allow it to do even more.

    Not sure why anyone prefers to choose locked in options

  • Agree, as long as models are interchangeable, it doesn't make sense to be locked into a single lab's managed agent platform. You probably want to swap between models and own the agent state.

    https://github.com/omnara-ai/omnara - this is a self hostable agent API that I'm working on. It stores the state of all agents in a postgres db you can easily query, rather than a local json file or sqlite file per agent.

  • Is GLM 5.3 Flash that good? I'm using it through atlascloud for my current project and testing performance against opus and gemini models. I think I'm mostly concerned about speed because they are mostly doing tool calls.

    Also yes to an open runtime.

  • The best answer I’ve come to thus far is the model we (estuary.dev) are building out now: offering mcp.estuary.dev with tools for creating a sandbox with our CLI pre-installed, a tool for requesting that a tightly scoped access token be injected into a named sandbox file (this is the approval gate), and a tool for executing arbitrary commands in the sandbox (presumably our flowctl CLI, but let the model rip).

    The intent is that anybody can drive it from Claude/ChatGPT/Pi on their phone after MCP sign-in (oauth), the model has full computer use capability, but we can also leverage it to build guided agent workflows in our own dashboard.

  • Libraries such as agent development kit (https://adk.dev/) provides abstraction over multiple LLM vendors, long-term memory (persistance + compaction) and allow us to manage subagents & their lifecycles. Vendor neutral memory & context management is a challenge as default long-term memory uses vertext AI (gemini) in ADK.

  • I built several harnesses in different products over the last two years. Fully agree with you that doing it right is a rabbit hole. Certain system properties that you almost always want in a harness used within a SaaS (for example) are non-obvious at the start and require certain architectural choices. It's easy to start down a path and then find a gap a couple days before launch.

    Async tool calls, having the agent wait indefinitely for a human response, and showing a form or questions to the user via a tool call are a few common capabilities that come up that a product manager might miss at first.

    This is why I've been building Nvoken. LLM agnostic, ergonomic SDKs, flexible tool call patterns, tenant and user-aware budget enforcement, etc.

    I'd really appreciate any and all feedback on this! It gives you some free tokens on signup and it's super quick to try.

    https://nvoken.com

    • > Async tool calls, having the agent wait indefinitely for a human response, and showing a form or questions to the user via a tool call are a few common capabilities that come up that a product manager might miss at first.

      All of this is specified in the ACP spec, so if you build your agents from that - you don't end up skipping features.

      Also vital is proper prompt caching, tool design and some connection retry mechanism.

      1 reply →

  • > Where does the state persist?

    Spider men meme of developers pointing at each other thinking "Not it".

  • Agents are the wrong paradigm entirely and have limited places where they actually belong.

    Going off and searching the web isn't really it.

    You need to create 'new worlds' where they can operate best - and even then constrain what it does.

  • I think things like onecli are the direction we will take. The secrets and state will be proxied api calls.

I launched Epho a few weeks ago as an API like this but for all harnesses: https://epho.io

I built it primarily for ourselves: we are building an AI data engineer, and we need a way to run many of them in parallel securely. An API for this seemed like the most obvious path forward. It makes it trivial to bring agentic capabilities into any product surface without having to deal with sandboxes, reliability issues, compatibility problems, and more.

I think it also makes sense from OpenAI's perspective to do this, but also we did find ourselves needing to change models and harnesses quite a bit, which is why I think this needs to be a layer of its own above the labs. It also needs to be a layer above the sandboxes, since many of them are quite brittle.

Overall, I expect a lot of the agent implementations to move in this direction. I think this is a lot saner for engineers to implement and maintain, and it makes it trivial to build agentic stuff into products.

  • I've commented about this before, I think many LLM based apps nowadays are at risk of being replaced by a product straight from the labs once they prove to be successful.

    We've seen this pattern with Apple making their own version of an app that was previously popular on the app store.

    The labs are in a perfect position to do this - they have a bunch of data on what's being used and they have direct access to their own models/compute. If an external service is popular, it's relatively trivial for them to estimate how much additional profit they're leaving on the table.

    If the usecase isn't far from their core business (and things like this absolutely aren't), with their size, why wouldn't they eat other people's lunches?

Buried in there, note you can opt to self-host your sandbox

https://developers.openai.com/api/docs/guides/agents-api/env...

That makes this much more enticing, and potentially eases transition between providers.

  • Then why tf do i need their api

    • Some people/companies/whatever might like the convenience and scalability of managed solutions, especially if you're say, just building something simple like a Slack bot with your custom workplace tools/data.

      Yes, the lock-in is real and only good for OpenAI, but there's absolutely demand for managed services where you defer the responsibility of security patching; scaling; uptime, etc to a third party provider. Just like why people use AWS/GCP/etc over bare metal in a colo.

    • The self-hosted environment is just the backend for shell calls the agent wants to make. The inference bits, thread persistence, and (optionally) mcp/tool calls happen from the API.

    • Going to be GitHub self hosted runners all over again, you pay for the API and also pay for your own self hosting.

I've recently had great success running codex in a regular qemu VM and using codex remote control to talk to it from my phone.

Honestly works extremely well as a personal assistant.

I can see why turning it into an API makes sense, just be aware you might not need to lock yourself in if you can setup your own VMs.

  • Yes, I do the same with Claude Code. Create an instance on the server for a project and then can create sessions from any device, close my laptop while claude code keeps working, etc. without losing the convenience of dedicated apps.

  • The key here is that they are _not_ just turning "running codex on a VM" into an API. Their harness is running outside a VM, interacting with a VM when needed. See the diagram in their post. This allows them to scale the agent runs independently from the VMs. That's why they call it "managed Codex harness", it's a different version than what you run.

  • I do the opposite. I have a Slack bot that communicates with an app on my Mac mini that dispatches agents for tasks. It knows all my projects and also has a scheduler that uses the Herdr API. That way I can have things running on my Claude/Codex subs at home 24/7.

    Setting up all my code, environment, context, etc in the cloud on VMs seemed like a lot so instead I send back tasks to my Mac mini(s) that are running at home.

  • Yep I run `claude remote-control` as daemons (systemd/launchctl) on whatever paths/repos I wanna be able to create a session from on-to-go.

    Works really well and is a great use case for work laptops. Same shell, same memories, same sessions

  • I've been running Hermes inside a remote docker container connected to Slack bound to a Codex account. It's actually pretty great, I prefer this approach for a lot of things. Because it's in a Docker container I have 100% control over the configuration. It may do some crazy stuff, but I know it's not going to start exfiltrating my AWS SSO tokens or SSH keys from my laptop.

  • I've done something similar by running pi within an xmpp wrapper on my server, so I can talk to it from any phone or computer. Works super well.

  • Do you have 1 long running session?

    • Codex remote control serve can run continuously.

      Sometimes start a new chat in the phone app, sometimes just add to the main one. Both seem to work ok.

      If I want the agent to wait for something I need to start a new chat in the iphone app.

I think the line between regular LLM "endpoints" and agents/harnesses is going to become more and more blurry until it's a meaningless distinction.

When you're using ChatGPT/Claude/Gemini etc. you're basically already interacting with some backend harness with tools etc., not a raw LLM. Just give it a computer and be done with it.

I already find myself using Claude Code / Antigravity (via web) instead of Claude / Gemini, even for tasks unrelated to coding. Why use a limited version?

  • This bothers me so much with the existing offerings. I start with the chat interface then as soon as I want to get technical/run scripts/automation, I have to copy the context into a fresh code session. So cumbersome.

This idea of remotely hosting the agent harness is honestly backwards to what I need.

In so many cases, all the friction is about how to provision access to local data so the agent can work. So you started with the problem of how do I integrate an agent that is running locally with data that is hosted locally, and you have to deal with a bunch of security, data sensitivity and management issues around that. Now you moved the agent to a remote host - pretty much all your problems are worse: now I have a remote agent reaching into my infrastructure to deal with.

I'd much rather the inverse of this: let me run the agent local but provide secure remote hosted sandboxes. That actually solves a real problem because the sandbox running locally means breaking out of it directly intersects your local infra, whereas if it runs in a managed hosted environment I can leave the provisioning and management of that to someone else.

  • The end goal is not you watching what the agent is doing, verifying, then accepting its changes. In the ideal scenario of automation, the agent does it on your request, doesn't matter wherever you are.

    Kind of slack-button-click-to-fix-something workflow.

I actually have a good use case for this. For my project, I run a lot of Codex sessions in parallel (via Codex SDK[0]), because they are solving self-contained tasks (building crawlers for websites) and in theory I could scale it to hundreds or thousands of parallel sessions. But my VPS can handle maybe 10 parallel sessions max.

Btw, the crawlers are for classical music websites, the project is https://classicalbot.com/ .

[0] https://learn.chatgpt.com/docs/codex-sdk

I believe is not a good idea for the model providers provides a Agent Infrastructure or hosting service.

This area should be open source and supported by the cloud providers. Because I don't really want to be locked to a model provider when I am building my agents.

Actually this is happening, I found couples:

- https://flueframework.com from Astra - https://eve.dev from Vercel - https://fastagent.sh looks more independent, cloud neutral

There should be more and more options, the OpenAI Agent API may be another GPTs

  • It's entirely possible future models will refuse to answer if they notice you're using an external harness.

    Instead they'll point you to their respective vendor APIs for the specific use cases.

    We're talking about trillions in value to be captured, they'll try everything.

Though I'm not surprised by this offering, I feel like I need some time to absorb it. It feels like the stepping stone to the next big thing.

It's going to destroy a lot of startups which were monetizing this exact idea. But clearly it's a low-hanging fruit so it makes sense that OpenAI would do it.

I've had great success with the OpenAI agents SDK [0]. This way I've been able to build the sandbox + slack + knowledge-bank integrations independently and be very strict with what I expose to OpenAI.

Looking at the Agents API, it seems like it offers similar capabilities, but reduces the need for hosting? So I get it from a business standpoint, but hosting a python service is very easy now a days, so I don't see the point as a consumer.

[0]: https://openai.github.io/openai-agents-python/

  • Why not just build this yourself, you literally have AI, why wall yourself into an OpenAI garden. These sandboxed environments are trivial to build.

    • I found that trying to keep up with their API updates and changes is more trouble than its worth, even with AI. The agents would need to reverse engineer from the OpenAI SDK source anyways, so why not cut the middleman?

      If I wanted something portable for multiple providers, I would of course not use the OpenAI SDK at all. It's a conscious choice to go with OpenAI (in this design), it fits for my company at the moment.

I think in time people will realize harness is essentially a more complicated .vimrc or .zshrc;

And yes, you can install gigantic plugins in those places - e.g. Codex; but the point is everyone will have exactly what they have customized towards. The more atomic a building block is, the easier it can be adapted into any kind of configuration.

I think the pain of selling a harness is if your target market understand what a harness is, then they can build it to exactly how they'd like it without much effort. If they don't, then the harness wouldn't be very useful to them in the first place.

This is pretty interesting in a lot of non-surface-level ways.

I can see OpenAI pushing for this as a sort of more durable moat compared to the now huge number of agentic harnesses that run on your own machine.

This might be getting the foot into some sort of bundling as well. Like unrestricted models or custom fine tuned agents inside this and not providing direct APIs to those endpoints.

That being said I don't see a lot of reasons for people to jump on this if it doesn't bundle something killer. Like to me the fact that GPT Work runs on your own machines and all the artifacts and work in progress there for you to look at is sort of the whole point. I don't just want a final artifact.

  • >GPT Work runs on your own machines...is sort of the whole point.

    Which is also why they want to remove it from your machine. Call it conspiratorial, but I keep thinking about "You'll own nothing and be happy." It seems like the industry is quickly moving in a direction where devices are turning into gateway into the cloud, and personal computing will turn into a hobby that prices out the average individual.

Their showcase examples[0] link to GitHub but the links 404. Like this one for the Slack agent: https://github.com/OpenAI-Early-Access/agents-api-python-pre...

Guessing this an early release not quite ready for the public? Interesting that there's a 'OpenAI-Early-Access' GitHub user, though of course with no public repos. Presumably when its actually public they'll move the example agent repos to another GitHub user.

[0] https://developers.openai.com/showcase/agents-api-slack-bot

edit: Maybe someone from OAI saw my comment because the links are now fixed! And they point to a public repo under the openai org: https://github.com/openai/openai-cookbook/tree/main/examples...

It's interesting to me that the agents comparison page[0] doesn't list codex's app-server as an option.

I've found the app-server to be the most flexible, compared to the raw Responses API or Agents SDK.

Certainly seems like everyone is still figuring out the right interface here.

Also of note, since GPT-5.5 or so, Codex doesn't even use the Responses API as intended, but instead a "lite" version where they manage the context more manually (like sending the full transcript or using a custom web.run tool instead of the provided `web_search` tool).

If you follow the docs, it will lead you down a lot of well-intended functionality, but most of it is thrown away in their most successful harness.

[0]https://developers.openai.com/api/docs/guides/agents#compare...

Why would you choose api vs sdk . Sdk in a sandbox feels much better .

What I want (which I don’t think exists?) is a way to trigger turns that the user can monitor in the codex application. I.e., when event X happens, my application triggers Codex to take a turn with input Y, which the user can monitor through codex. Right now the only way to get close to this is with polling or essentially rewriting a codex-like frontend.

  • I just wrote my own VR harness in a weekend with Astra. It mentioned an SDK for exactly this in passing, but it was an experimental personal project so I didn’t bother to review the code.

    I was doing exactly what you’re describing. I think this is a ToS violation for anything other than personal use though.

  • do you mean like a cloud agent provider? What we're working on at noriagentic.com may be relevant -- you can fire events from slack/web/cli to kick off an agent in a box and talk to it as if it was running local

    • Do you guys support projects that span multiple repositories? (and can create multiple PRs across them?)

  • You can give the agent a tool (or bash script) which waits for events. Agent calls it and the tool sleeps until an event happens then returns it to the agent.

Six months into customizing my own Claude Code harness, I've settled on assuming Anthropic and OpenAI will just handle all of it, except turning my own flows into skills.

It's actually a really great idea, but it doesn't have to go beyound existing Responses or Chat Completions APIs.

We built that in my current company and it works wonders to just script entire persistent workflows with a simple SDK.

would love if it would be possible to allow suer and signing with the open ai account and use exiting subscription.

anyone knows how to do that and implement agent api with user actual account?

Pretty good abstraction. Setup your sandbox with dependencies, build plugins - agent works. Tested it with OpenAI for the last month while it was in preview

Since a week or so everything I ask codex to do, no matter how small, uses at least 1% of my weekly limits and like 5% of my 5h limit. It's getting so bad I'm thinking of just canceling my OpenAI subscription, because this has no use anymore.

  • Check which model you're using, Astra is the new default, but also the most expensive

    • That's the thing. I did notice that, and switched back to my favorite (5.6 sol, medium). No difference.

      Looks to me like they really took down the quotas, especially anything in codex. Either that or it's something else, perhaps in codex?

  • I get the same. It sits there and spins for a bit then as soon as it spits out something, my 5h is 5-10% lower, whether it's asking it to do code review over a significant code base or just asking it to change a config value.

  • I also signed up for a new account and it's right back to working how it used to. They absolutely do not consume tokens equally across accounts. I did TONS of work on the new account and barely made a dent, even on Astra. Old account chews through 20% like it's nothing

    • That sounds like large amounts of context (maybe from memory or history?) are chewing through your quota, context that hadn't yet had a chance to build up in your newer account. That's just a guess, I'm not an account holder there or anything so I can't try to re-create it on my end. You could try to erase history on your old account too, too see if it makes a difference. 'Course, then you'd lose all that history!

    • If true, that sounds like something that could actually be monitored by third parties, similar to the performance degradation trackers.

The pricing on this is a bit confusing. Does each execution of an agent session create a new environment? And is that environment then billed for at least a full hour (despite prices being quoted per 20 minutes), after which it naturally expires? Is there a way to deliberately shut down an environment so you don't have to keep paying for it?

This was sorely needed.

Hopefully this kills the need to use the CLI and we can just use the API instead.

  • Why would you prefer to use the API if you can have something running locally?

    We use the OAI API because there is no local equivalent, I'm assuming this is just the codex client running on the cloud?

Hey guys AAAAAH WE ARE ABOUT TO DESTROY THE PLANET anyway heres an API reference so you can build durable codex harnesses OMG WE WILL KILL ALL HUMANS ITS GONNA HAPPEN GUYS let us know if you spot any issues IMMANTISE THE ESCHATON, ALL HAIL THE BASILISK ok guys?