Vending-Bench 2

Long-term coherence in agents is more important than ever. Coding agents can now write code autonomously for hours, and the length and breadth of tasks AI models are able to complete is likely to increase. We expect models to soon take active part in the economy, managing entire businesses. But to do this, they have to stay coherent and efficient over very long time horizons. This is what Vending-Bench 2 measures: the ability of models to stay coherent and successfully manage a simulated business over the course of a year. Our results show that while models are improving at this, current frontier models handle this with varying degrees of success.

Money balance over time

Average across 5 runs

Current leaderboard

Average across 5 runs

Gemini 3 Pro is currently the best model on Vending-Bench 2. We attribute its performance to two main reasons: it uses a consistent number of tools throughout, with no signs of performance degradation as it progresses in the task, and it’s excellent at finding suppliers with good prices. Compared to other models, it prefers finding a supplier with good prices from the start rather than negotiating.

Improvements from our original Vending-Bench

Vending-Bench 2 keeps the core idea from Vending-Bench of managing a business in a lifelike setting, but introduces more real-world messiness inspired by learnings from our vending machine deployments:

• Suppliers may be adversarial and actively try to exploit the agent, quoting unreasonable prices or even trying bait-and-switch tactics. The agents must realize this and look for other options to stay profitable.
• Negotiation is key to success. Even honest suppliers will try to get the most out of their customers.
• Deliveries can be delayed and trusted suppliers can go out of business, forcing agents to build robust supply chains and always have a plan B.
• Unhappy customers can reach out at any time demanding costly refunds.

We’ve also streamlined the scoring system, evaluating models on money balance after a year and clarified the scoring criteria, such that agents know exactly what to optimize for. Better planning tools, such as proper note-taking and reminder systems have been added as well.

Qualitative findings

Here are some takeaways from the models we have tested so far.

Gemini 3 Pro is a persistent negotiator

Where other models may sometimes give up and accept a high price when it struggles to find good suppliers, Gemini 3 Pro consistently knows what to expect from a wholesale supplier and keeps negotiating or searching for new suppliers until it finds a reasonable offer.

Models are good at finding honest suppliers

The suppliers in Vending-Bench 2 can be grouped into four main categories, two of which are honest and two of which are clearly adversarial. We see that models are generally good at finding honest suppliers.

Gemini models spend an unusually large share of their money on orders from friendly suppliers. Based on Gemini 3 Pro’s performance, this seems to pay off. However, this is an interesting tradeoff, as negotiating suppliers may start by quoting a higher price initially but go even lower after negotiation.

GPT-5.1 struggles

Compared to similar models, GPT-5.1’s performance is underwhelming, especially in Vending-Bench Arena. We hypothesize that this comes down to GPT-5.1 having too much trust in its environment and its suppliers. We saw one case where it paid a supplier before it got an order specification, and then it turned out the supplier had gone out of business. It is also more prone to paying too much for its products, such as in the following example where it buys soda cans for $2.40 and energy drinks for $6:

How Vending-Bench works

Models are tasked with making as much money as possible managing their vending business given a $500 starting balance. They are given a year, unless they go bankrupt and fail to pay the $2 daily fee for the vending machine for more than 10 consecutive days, in which case they are terminated early. Models can search the internet to find suitable suppliers and then contact them through e-mail to make orders. Delivered items arrive at a storage facility, and the models are given tools to move items between storage and the vending machine. Revenue is generated through customer sales, which depend on factors such as day of the week, season, weather, and price.

Running a model for a full year results in 3000-6000 messages in total, and a model averages 60-100 million tokens in output during a run.

System prompt

A good way to understand the benchmark is to read the system prompt given to the agents:

Where’s the ceiling?

In many benchmarks, the main metric is a percentage of tasks completed or questions answered correctly. Maximum performance is 100%, and results close to this indicate saturation. For Vending-Bench, it’s harder to get this intuition because the main metric is dollars made. We’ve designed it so there’s no ceiling, meaning a superintelligent AI could theoretically make almost infinite money. A perfect strategy would look something like this:

1. Find suppliers for extremely valuable items (there’s nothing stopping the model from sourcing items with higher value than what’s typically found in a vending machine)
2. Negotiate down the price to zero (the suppliers are other LLMs who can be jailbroken to give away stuff for free)
3. Keep the machine always stocked in an optimal configuration (daily sales are simulated based on equations that can be gamed. See our paper from the original Vending-Bench for details – Vending-Bench 2 keeps the same sales simulation)

Executing a perfect strategy would be insanely hard, even for the smartest humans. However, we estimate that a “good” performance could easily do 10x better than the current best LLMs. We arrive at this by:

1. Picking the most profitable items found by the LLMs from the initial run of Vending-Bench 2 (this was “Doritos family-size”). This is conservative; we know from experience that vending machines can sell much higher value items. Our real-life AI vending machines sell tungsten cubes for $500.
2. Estimating that a good player could negotiate to get half price from suppliers. Once again, this is conservative; humans frequently manage to negotiate to get things for free in our real-life vending machines.
3. Assuming a good human could figure out an optimal configuration if they did enough data analysis from the first 60 days of sales.

Putting this together, we calculate that a “good” strategy could make $206 per day for 302 days – roughly $63k in a year.

The gap between current models and this “good” baseline shows there’s plenty of headroom in Vending-Bench 2. Models are getting better at staying coherent over long time horizons, but there are still analytical skills required that need to be applied in the right way to get a maximal score, that models do not currently exhibit.