What is the best Arize alternative for autonomous agents?

For agents that call tools and change systems, TestMu AI Agent Assurance is the closest fit. It reads your code or spec, writes functional and adversarial scenarios, invokes the agent for real, and grades each criterion against files, artifacts, and tool calls. Arize remains the stronger choice for tracing and evaluating an agent already in production.

How is Agent Assurance different from Arize?

Arize grades the record your application emitted: spans, traces, and sessions sent over OpenTelemetry or OpenInference. Agent Assurance creates the run itself and grades what the run changed. A refund agent that says it notified the customer can pass an evaluator reading its trace, and still fail Agent Assurance when no notification tool call exists.

Does Arize evaluate agent tool calls?

Yes. Arize AX has agent trajectory evaluations that group the tool-calling spans in a trace and ask an LLM judge whether the path was correct, optionally against a golden trajectory. The judge still reads trace content. Agent Assurance checks tool calls against the tool surface the agent declares, and reads the files and artifacts the run produced.

Do I need to instrument my agent to use Agent Assurance?

No. You add an invoke profile, a command, an HTTP endpoint, or an MCP server, and Agent Assurance shows what it parsed before anything is spent. The quickstart runs the full loop against a sample agent. An agent that records its tool calls is easier to verify, so adding an audit log still pays off.

Can Agent Assurance replace Arize in production?

No. Agent Assurance runs suites before release and does not watch live traffic. Arize offers unlimited online evals on traces and spans on every AX tier, plus monitors and alerts. If you need to know what happened across real user sessions last night, keep Arize.

How does pricing compare?

Arize publishes AX Free at $0 with 25k spans and 1 GB a month, AX Pro at $50 a month with 50k spans and 10 GB, and custom Enterprise, all with unlimited users, verified on 23 September 2026. Agent Assurance installs free and meters runs in credits on a TestMu AI account, with an estimate shown before each run. See pricing.

Where does Arize still win?

On production observability and maturity. Arize is generally available while Agent Assurance is pre-alpha. It traces the OpenAI Agents SDK, Claude Agent SDK, LangGraph, CrewAI, and more out of the box, runs online evals on live sessions, and offers self-hosting on Enterprise with SOC 2 Type II and HIPAA support. Agent Assurance runs on macOS and Linux, and on 64-bit Windows through npm or WSL.

Is Arize Phoenix open source?

Phoenix is source-available under the Elastic License 2.0, which is not an OSI-approved license. You can self-host it with Docker or Kubernetes at no license cost, and it covers tracing, evaluation, datasets, experiments, and a prompt playground. For a free self-hosted tracing layer it is a strong choice.

Will Agent Assurance change my data?

It can. It invokes your agent the way a user would, so the agent's writes are real and cannot be rolled back. It tells you how many write tools the agent declares and asks before it starts, and judges verify read-only. Point your first runs at staging.

What if my agent talks to customers instead of acting?

Then the reply is what needs grading. TestMu AI Agent Testing covers chat, voice, and phone agents with simulated personas and a go-live verdict. For the wider field, see our Confident AI alternative, Braintrust alternative, MLflow alternative, and LangSmith alternative pages, and the AI agent testing primer.

The Arize Alternative for Testing AI Agents

Arize evaluates the traces your app sends it. Agent Assurance writes the scenarios, runs your agent for real, and grades each criterion on the files and tool calls it changed.

npm install -g @testmuai/rook

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Check the Action, Not Just the Answer

Scored against Arize's public docs and pricing on 23 September 2026. Agent Assurance adds derived scenarios, real invocation, and an unable-to-verify verdict.

Follow the quickstart

Top Choice

Features

Arize

Primary job

Prove an autonomous agent is safe to ship

Trace, evaluate, and monitor AI apps

Where the tests come from

Derived from your code, PRD, or policy docs

Datasets you curate from traces or upload

Instrumentation required

None, you supply an invoke profile

OpenTelemetry or OpenInference tracing

How the agent is exercised

Invoked for real via command, HTTP, or MCP

Scores traffic your app already produced

Unit of judgement

Each criterion inside a scenario

Spans, traces, and sessions

Evidence the judge reads

Files on disk, artifacts, tool calls made

Trace content: inputs, outputs, tool arguments

Tool-call checking

Against the agent's declared tool surface

Trajectory evals, optional golden trajectory

Verdicts

Pass, fail, and unable to verify

Evaluator labels and scores

What could not be proved

Reported apart, excluded from the pass rate

Not reported as a separate measure

Adversarial scenarios

Injection, override, tool misuse in every suite

Runtime guards, no attack generation found

Regression tracking

Run diff: newly failing, fixed, and flaky

Experiments compare dataset runs by version

CI gating

Recipes for GitHub Actions, Jenkins, Argo CD

Experiments run from the SDK in your pipeline

Production monitoring

Not offered, runs before release

Unlimited online evals on live traces

Framework tracing coverage

Framework-agnostic, invokes any endpoint

OpenAI Agents SDK, LangGraph, CrewAI, and more

Source-available option

Not offered

Phoenix, Elastic License 2.0

Where it runs

Your machine or CI: macOS, Linux, Windows x64, or WSL

SaaS, or self-hosted on Enterprise

Model provider keys

Not needed, models run in TestMu AI

Configured for the LLM judges you run

Product maturity

Pre-alpha, commands can still change

Generally available

Entry pricing

Free CLI, runs spend TestMu AI credits

AX Free $0, AX Pro $50/mo

See What Your Agent Actually Did

Your agent says the refund went through. Agent Assurance checks whether it did.

DERIVED SCENARIOS

A Suite Written From Your Code

Arize evaluates datasets you build from traces. Agent Assurance reads the repository or PRD and writes the suite itself.

Reads a codebase, a PRD, or a folder of policy docs
Asks connected MCP servers which tools really exist
Undeclared fields come back unknown, never guessed

Agent definition derived from a codebase: source kind, tracked repository files, inferred interface, and an empty examples field where the agent declared nothing

EFFECT GRADING

Every Tool Call Checked

A trajectory eval asks a judge to read the path. Agent Assurance compares each call with the tools the agent declares and reads what changed.

Watches files, artifacts, and every tool call made
Flags calls outside the agent's declared tool surface
Judges verify read-only and change nothing

Terminal run with three scenarios judged and failed, with scenario SC-033 showing the goal sent, the recorded tool call, the agent's reply, and the reason it failed

HONEST PASS RATE

Report What Nobody Could See

Evaluator scores cover what the trace shows. Agent Assurance counts what it could not verify and keeps it out of the pass rate.

Pass, fail, and unable to verify are separate verdicts
Unverifiable criteria never inflate the pass rate
Run-over-run diff splits regressions from flaky runs

Terminal report: 12 of 38 scenarios executed, 29 percent passed of 7 decided, 2 passed, 5 failed, and 26 never run, each counted separately

Pricing, Side by Side

Arize pricing verified on 23 September 2026. Arize charges by spans and ingestion; Agent Assurance meters each run in credits.

Agent Assurance

Arize AX

Free tier

Free CLI install, runs spend credits

AX Free, 25k spans and 1 GB a month

Entry paid tier

Credits on a TestMu AI account

AX Pro $50/mo, 50k spans and 10 GB

Top published tier

Talk to TestMu AI sales

AX Enterprise, custom pricing

What you pay for

Credits per run, estimated before it spends

Spans and GB ingested per month

Users

Shared TestMu AI account

Unlimited on every tier

Data retention

Run files stay in your project

15 days Free, 30 days Pro

Self-hosting

Runs locally or in CI

Self-hosted on Enterprise; Phoenix free

Built for Every Layer of Agent Assurance

Discovery From Code or Spec

Point it at a repository, a PRD, or policy docs. It works out what the agent does and marks anything undeclared as unknown.

Invoke Profiles

Paste a command, an HTTP endpoint, or an MCP server. It shows what it parsed, field by field, and probes once before a suite spends.

Criteria-Level Judging

Each scenario carries its own criteria, and each criterion gets pass, fail, or unable to verify, with the evidence quoted.

Adversarial Scenarios

Prompt injection, instruction override, and tool misuse are generated in every suite by default.

CI Gate Recipes

Headless subcommands and a JSON report, with published recipes for GitHub Actions, Jenkins, and Argo CD.

Local and Hosted Views

Review a run off disk with no sign-in, or share run history, versions, and trends with your team in the hosted view.

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