Same model, 68% to 88% fewer tokens: Antigravity CLI vs Claude Code vs Codex, measured

Google stopped serving Gemini CLI to personal accounts on June 18, 2026 and moved people to its new Antigravity CLI ( agy ). Antigravity can run Claude models too, which makes a rare test possible: the same model, Claude Opus 5.5, in two different coding tools. So I ran Antigravity CLI, Claude Code and Codex on the same prompts, 44 runs in total, and checked every game they built in a headless browser.

Most of this is each tool's own instructions and tool definitions, which go out again with every request.

With the same Opus 5.5, Antigravity read 68% to 88% fewer input tokens than Claude Code, wrote 40% fewer output tokens and finished 27% faster. Claude Code's games were longer (451 lines against 236), and Claude Code put each run at $0.37 at API prices. Antigravity and Codex show no price on a subscription.

All 12 games worked: the score rises when bricks break, level 2 appears, lives go 3, 2, 1, 0. My automatic check could not read the score in two of the Codex games, so I checked those by hand; both scored.

Antigravity's JSON reports input_tokens and cache_read_tokens separately, and its documentation does not say whether one contains the other. In the Opus runs the cache reads (15,381) were larger than the input (9,822), so there they cannot be inside it. I show both: the reported input as the low end (88% fewer) and input plus cache reads as the high end (68% fewer). Even the high end is far below Claude Code.

In Antigravity one tool already added about 280 to 460 tokens and the next 29 added little. All four setups now seem to load a tool's full definition only when it is used.