Skip to content
SPECIFICTION
Get listed

Strands Evals

strandsagents.com

Free plan WindowsmacOSLinuxAPISelf-hosted
Visit strandsagents.com
Spec score 7.6 #21 of 28 in AI Agent Evaluation Tools

What it is

Strands Evals is an open-source Python SDK and CLI for assessing AI agent behavior during development and after deployment. It scores outputs and trajectories, helps diagnose failures, probes unsafe behavior, and can simulate users and tools. Evaluators can target an output, tool call, trace, or full session, and several can be combined in an experiment. Built-in groups cover quality, safety, multimodal responses, agent behavior, and skill selection and instruction following. Deterministic checks run without an LLM judge; custom logic can be added by extending the Evaluator class. Install the package with pip as strands-agents-evals to use its Python API or the strands-evals command. The CLI can generate experiments, validate JSON, run evaluations, render reports, and diagnose sessions. Trace providers include AWS CloudWatch Logs, Langfuse, and OpenSearch. Evaluations can use production or staging traces without rerunning their agents. The quickstart uses Amazon Bedrock with Claude as its default judge and requires credentials authorized to invoke Claude. Red-teaming is marked experimental. The SDK is free and supports API, Linux, macOS, self-hosted, and Windows environments.

Spec sheet

Purpose
Strands Evals measures agent behavior before shipping and after deployment by scoring outputs and trajectories, diagnosing failures, probing unsafe behavior, and simulating users and tools.Read 4 Oct 2026 · strandsagents.com
Intended users
The SDK is presented for developers who want to validate agent behavior, measure improvements, and evaluate agents during development cycles.Read 4 Oct 2026 · strandsagents.com
License
The maker’s announcement identifies Strands Agents as an open-source project licensed under Apache License 2.0.Read 4 Oct 2026 · strandsagents.com
Built-in evaluators
Built-in evaluator groups cover quality, safety, multimodal responses, agentic behavior, and skill selection and instruction following.Read 4 Oct 2026 · strandsagents.com
Custom evaluators
Developers can implement domain-specific evaluation logic by extending the base Evaluator class.Read 4 Oct 2026 · strandsagents.com
Default judge
The quickstart states that evaluators use Amazon Bedrock with Claude as the default judge model, and that running its example requires credentials authorized to invoke Claude.Read 4 Oct 2026 · strandsagents.com
Deterministic checks
Deterministic evaluators run code-based checks without an LLM judge and include Equals, Contains, StartsWith, ToolCalled, StateEquals, and SkillInvoked.Read 4 Oct 2026 · strandsagents.com
Evaluation levels
Evaluators can assess a single output, tool call, trace, or full session, and multiple evaluators can be combined in one experiment.Read 4 Oct 2026 · strandsagents.com
Experimental feature
The red-teaming API is marked experimental and may change in a minor release.Read 4 Oct 2026 · strandsagents.com
Local and remote use
The SDK can run evaluations against production or staging traces without rerunning the agents that produced them.Read 4 Oct 2026 · strandsagents.com
SDK and CLI
The package installs with pip as strands-agents-evals and provides both a Python API and the strands-evals command-line interface.Read 4 Oct 2026 · strandsagents.com
Test generation and CI
The CLI can generate experiments, validate experiment JSON, run evaluations, render reports, and diagnose sessions; its documentation shows validation and evaluation steps in a CI workflow.Read 4 Oct 2026 · strandsagents.com
Trace integrations
Trace providers fetch data from AWS CloudWatch Logs, Langfuse, and OpenSearch, with optional package extras for Langfuse and OpenSearch.Read 4 Oct 2026 · strandsagents.com
Trace mapping
Session mappers include support for Strands in-memory spans, LangChain OpenTelemetry spans, and OpenInference instrumentation such as Arize Phoenix.Read 4 Oct 2026 · strandsagents.com

Plans and prices

Strands Evals SDK Free Open-source Python SDK and CLI · install with pip · model-provider and trace-provider access may require separate credentials or services Read 4 Oct 2026 · strandsagents.com

Every Strands Evals plan and price →

Strong points and limits

Strong points

  • Evaluations can target outputs, tool calls, traces, or sessions.
  • Deterministic checks can run without an LLM judge.
  • CLI supports validation, runs, reports, and diagnosis.
  • Trace providers include CloudWatch Logs, Langfuse, and OpenSearch.
  • Open-source SDK and CLI are listed as free.

Limits

  • Quickstart example requires authorized Claude invocation credentials.
  • Red-teaming API is experimental and may change in a minor release.
  • Some model and trace provider access may need separate credentials or services.

Who it suits

It suits developers who want to validate agent behavior, measure changes, and evaluate agents during development cycles. Teams working with traces can also assess production or staging sessions without rerunning the agents.

Verdict

Strands Evals offers code-based and model-judged evaluation options, with SDK and CLI workflows for experiments and trace analysis. The default judge setup requires authorized Claude credentials, and red-teaming remains experimental.

Where Specifiction places it

Alternatives to Strands EvalsAll alternatives →