Agent-TARS

Agent-TARS is a browser agent developed by the TARS team, distributed as an npm CLI package with powerful browser automation capabilities.

Installation

uv sync
npm install -g @agent-tars/cli@0.3.0

Activate .venv (or use uv run bubench ...) before running bubench commands.

Requires Node.js 18+.

Configuration

Configure Agent-TARS in the root config.yaml under agents.Agent-TARS:

agents:
  Agent-TARS:
    active_model: gpt           # active model profile
    models:
      gpt:                      # OpenAI model
        model_provider: openai
        model_id: gpt-5.4
        api_key: $OPENAI_API_KEY
        browser_control: hybrid
        timeout: 300
      claude:                   # Anthropic model
        model_provider: anthropic
        model_id: claude-sonnet-4-6
        api_key: $OPENAI_API_KEY
        browser_control: hybrid
        timeout: 300
      gemini:                   # Gemini via OpenAI-compatible endpoint
        model_provider: openai
        model_id: gemini-3-pro-image-preview
        api_key: $OPENAI_API_KEY
        base_url: $OPENAI_BASE_URL
        browser_control: hybrid
        timeout: 300
    browser:
      browser_id: local         # default local browser; see "Browser Modes" below to switch to cloud

Set active_model to the profile name you want to use by default, then switch at runtime with --model <name>.

Config Parameters

Parameter	Description	Example
`active_model`	Default model profile	`gpt`, `claude`
`model_provider`	Model provider	`openai`, `anthropic`, `volcengine`
`model_id`	Model ID	`gpt-5.4`, `claude-sonnet-4-6`
`api_key`	API key (use `$ENV_VAR` form)	`$OPENAI_API_KEY`
`base_url`	API base URL (optional)	`$OPENAI_BASE_URL`
`browser_control`	Browser control mode	`dom`, `hybrid`, `visual-grounding`
`browser_id`	Browser backend	`local` (default), `lexmount`
`timeout`	Task timeout (seconds)	Default `300`, overridable via `--timeout`

Browser Control Modes

Agent-TARS exposes browser interaction as two independent tool sets — DOM tools and vision tools — that the model can select from. browser_control determines which tool sets are available:

Mode	How it works	When to use
`dom`	Reads page structure and operates via DOM APIs (click, fill, etc.)	Fast and stable for standard web pages with accessible DOM
`visual-grounding`	Takes a screenshot, uses a vision model to locate elements by coordinates	Handles canvas, dynamic content, and elements missing from the accessibility tree
`hybrid`	Both tool sets exposed simultaneously; the model chooses per step	Best fault tolerance — DOM is tried first, vision acts as fallback

hybrid is the recommended default for benchmarking.

Browser Modes

Local Browser: Agent-TARS CLI launches a local browser. No extra parameters required.

browser:
  browser_id: local

The Agent-TARS CLI launches Chromium itself and does NOT honour local_proxy_* (a one-time WARNING is logged if you set them). If you need to reach sites your bare connection can’t (bloomberg.com, archive.org, etc.), switch to browser_id: lexmount — the international Lexmount region egresses outside mainland China. See Local Chromium Browser for the agent-by-agent support matrix.

Lexmount Cloud Browser: Connects to Lexmount via CDP. Apply for LEXMOUNT_API_KEY at browser.lexmount.cn (mainland China) or browser.lexmount.com (international) — see Lexmount Cloud Browser for the full flow — set it in .env, then reference it under browser in config.yaml:

browser:
  browser_id: lexmount
  lexmount_browser_mode: normal           # normal | light
  lexmount_api_key: $LEXMOUNT_API_KEY
  lexmount_project_id: $LEXMOUNT_PROJECT_ID

# .env
LEXMOUNT_API_KEY=your-lexmount-api-key

To add a proxy:

browser:
  browser_id: lexmount
  lexmount_browser_mode: normal
  lexmount_proxy_server: http://gw.example.com:823
  lexmount_proxy_type: external
  lexmount_proxy_username: $LEXMOUNT_PROXY_USERNAME
  lexmount_proxy_password: $LEXMOUNT_PROXY_PASSWORD

Usage

Basic Run

# Run first 3 LexBench-Browser tasks
bubench run \
  --agent Agent-TARS \
  --data LexBench-Browser \
  --mode first_n \
  --count 3

# Run Online-Mind2Web
bubench run \
  --agent Agent-TARS \
  --data Online-Mind2Web \
  --mode first_n \
  --count 3

Run All Tasks

bubench run \
  --agent Agent-TARS \
  --data LexBench-Browser \
  --mode all \
  --skip-completed

Evaluation

# --model-id matches the model_id used at run time
bubench eval --agent Agent-TARS --data LexBench-Browser --model-id gpt-5.4-mini

bubench eval --agent Agent-TARS --data Online-Mind2Web --model-id gpt-5.4-mini

Supported Benchmarks

✅ LexBench-Browser
✅ Online-Mind2Web
✅ BrowseComp

Agent-TARS npm package

Get Started

Features

Examples

Development

Installation

Configuration

Config Parameters

Browser Control Modes

Browser Modes

Usage

Basic Run

Run All Tasks

Evaluation

Supported Benchmarks

​Installation

​Configuration

​Config Parameters

​Browser Control Modes

​Browser Modes

​Usage

​Basic Run

​Run All Tasks

​Evaluation

​Supported Benchmarks

​Related Links

Installation

Configuration

Config Parameters

Browser Control Modes

Browser Modes

Usage

Basic Run

Run All Tasks

Evaluation

Supported Benchmarks

Related Links