Installation

The ABS CLI provides commands to initialize, run, and report on ABS sessions.

Prerequisites

• Node.js 18+ or Python 3.11+
• A package manager: npm, yarn, pnpm, or pip

Install via npm

npm install -g abslang

Verify the installation:

abslang --version
# abs v0.1.0

Install via pip

pip install abslang

Initialize a new project

abslang init my-agent-tests
cd my-agent-tests

This creates:

my-agent-tests/
├── abs.config.yaml    # Configuration
├── sessions/           # Your .abs.yaml files go here
└── README.md

Don't want to write YAML? Use the chatbot

Describe the behavior in plain language and abslang generates the .abs.yaml for you:

abslang chat
# Uses OPENAI_API_KEY, ANTHROPIC_API_KEY, or DEEPSEEK_API_KEY — whichever is set
# You: A customer asks for a refund. The agent should verify the order, process it, and confirm.
# → generates a complete .abs.yaml with evaluations, datasets, and chain checks

Run a session

abslang run sessions/order-status.abs.yaml

For more details on the CLI, see the CLI Reference.

Next steps

• Tutorial — a 20-minute step-by-step guide
• CLI Reference — full command documentation
• Runner — executing sessions against real agents