AgentOps vs Vertex AI Gen AI Evaluation Service
Both are agent evaluation tools. Here is how they actually differ on price, billing model and deployment.
AgentOps
MIT-licensed agent observability with session replay and rewind, integrating in two lines across 400+ frameworks. Its free tier meters events rather than runs, which makes 5,000 far smaller than it looks.
Vertex AI Gen AI Evaluation Service
Google's evaluation service, whose defining feature is adaptive rubrics - a unique set of pass/fail criteria generated per prompt, working like unit tests. Now branded under the Gemini Enterprise Agent Platform.
| AgentOps | Vertex AI Gen AI Evaluation Service | |
|---|---|---|
| Category | Agent Evaluation | Agent Evaluation |
| Our rating | 4/5 | 4/5 |
| Starting price | $40/mo | Per token plus GCP compute |
| Billing meter | event | No usage metering |
| Free plan | Yes | No |
| Free self-hosting | Yes, free | No or paid tier only |
| Best for | Teams debugging multi-agent systems who want session replay and broad framework coverage with minimal instrumentation effort, and who will move to the paid tier quickly. | Teams on Google Cloud running model migrations, prompt changes or fine-tuning comparisons, who want per-prompt evaluation criteria rather than a fixed metric set. |
Our verdict on AgentOps
AgentOps is the best agent debugging tool in this category, and the distinction from evaluation matters. Its session replay with rewind and point-in-time control lets you step back through an agent run rather than reading a flat trace after the fact, which is the right interaction model for systems whose failures are sequential. Add two-line initialisation across 400+ LLMs and frameworks, MIT licensing with the full app self-hostable, and it is unusually easy to adopt. The thing to understand before you plan around the free tier is the unit. Five thousand events sounds generous until you realise an event is each tracked item - every LLM call, tool call and action - so a single agent run emitting a dozen events means the free tier is a few hundred runs, not five thousand. For anything agentic that is days rather than months. Pro at $40 a month with unlimited events removes the problem entirely and is cheap, so treat the free tier as a trial and budget for Pro from the start.
Full AgentOps review →Our verdict on Vertex AI Gen AI Evaluation Service
Vertex AI's evaluation service has the most interesting single idea among the cloud platforms - adaptive rubrics. Rather than applying the same metric set to every prompt, it generates a unique set of pass/fail rubrics for each one, and the framing Google uses is exactly right - rubrics act like unit tests. Comparing two models becomes evaluating their responses against the same generated tests and comparing pass rates, which is far easier to reason about than comparing averaged similarity scores, and far more informative about what specifically broke. It also offers static rubrics, deterministic computation-based metrics like ROUGE and BLEU where ground truth exists, and custom Python functions, so you are not forced into model-based judging when a cheap check would do. Two things to note. It has been rebranded under the Gemini Enterprise Agent Platform, so a lot of documentation and comparison content references a name that has changed. And adaptive rubrics are themselves generated by a model, which means rubric quality varies and inherits the usual judge bias, on top of costing more inference than a fixed metric set.
Full Vertex AI Gen AI Evaluation Service review →Frequently Asked Questions
What is the main difference between AgentOps and Vertex AI Gen AI Evaluation Service?
AgentOps: Teams debugging multi-agent systems who want session replay and broad framework coverage with minimal instrumentation effort, and who will move to the paid tier quickly. Vertex AI Gen AI Evaluation Service: Teams on Google Cloud running model migrations, prompt changes or fine-tuning comparisons, who want per-prompt evaluation criteria rather than a fixed metric set. Both sit in Agent Evaluation, so the decision usually comes down to billing model and deployment rather than raw capability.
Which is cheaper, AgentOps or Vertex AI Gen AI Evaluation Service?
It depends entirely on your workload shape, because they meter differently - AgentOps bills on event and Vertex AI Gen AI Evaluation Service bills on no usage metering. Published starting prices are $40/mo and Per token plus GCP compute respectively, but those numbers are not comparable until you apply them to the same traffic. Use our cost calculator to model both against your own request volume and span count.
Can I self-host AgentOps or Vertex AI Gen AI Evaluation Service?
AgentOps: Yes, free. Vertex AI Gen AI Evaluation Service: No or paid tier only. Free self-hosting means no licence fee, not no cost - you still own the infrastructure, upgrades and on-call.