Antigravity CLI beats Gemini CLI in real-world testing despite Google's migration hiccups

Google decommissioned Gemini CLI on June 18, cutting off free and Pro users from the open-source terminal tool that had amassed over 100,000 GitHub stars. Its replacement, Antigravity CLI, is a closed-source Go binary invoked via the agy command—and a hands-on comparison suggests the swap actually works better in practice.

The test setup#

A developer tested both tools across four scenarios: speed, file editing capability, extension migration, and headless automation. The results challenged Google's marketing claims while revealing important functional differences.

Speed: Google promised Antigravity would be "snappier," but median response times were actually slower—3.97 seconds vs. 3.2 seconds on identical prompts. Antigravity won on consistency (responses clustered 3.5–4.2s) and clarity, printing only the answer instead of startup noise like "Ripgrep is not available."

File editing: This is where the divide became stark. Gemini CLI in non-interactive mode refused the task, returning: "I am unable to complete your request… because the necessary tool to write to files (write_file) is not available." Antigravity completed the job, spinning up a Python environment, running tests with pytest and mypy, and even generating analysis reports—all autonomously.

Extension migration: The developer created a custom extension with a manifest and migrated it successfully. Antigravity converted it to "skills" and executed commands correctly, though the test was limited to a simple extension; skills, subagents, and hooks went untested.

Automation: Gemini requires API keys (friendly to headless setups) but can't write files or run commands once authenticated. Antigravity requires browser OAuth on first login—a barrier for CI/CD pipelines—but executed shell commands and piped input cleanly afterward. Whether non-browser auth exists for production use remains unclear.

The hidden cost#

During testing on migration day, Gemini returned HTTP 503 errors ("this model is currently experiencing high demand"). Each failed request triggered automatic retries that burned through the free tier's 20-request-per-day quota on flash-lite, forcing the tester to enable billing for requests that never returned answers.

The verdict#

Antigravity is the more capable tool. It can automate file edits and command execution—features Gemini CLI lacks in non-interactive mode. It communicated in clear, step-by-step English narration rather than terse errors wrapped in Node.js stack traces. Extension migration worked, and reliability was better.