Antigravity

Bridge Claude with Google's Antigravity CLI (agy) — Google's successor to Gemini CLI. Get a subscription-backed second opinion or code review using your Google AI Pro/Ultra plan, without per-token API billing.

Best for: a subscription-backed second opinion if you have a Google AI Pro/Ultra plan, and larger-context reads. The Google-sanctioned successor to Gemini CLI. Not for: fine-grained per-edit automation — it's one-shot and experimental. For continuous review, use Codex via codex-pair.

Experimental

On agy ≥ 1.0.6 the headless -p mode prints the response to stdout (used directly); older versions / edge cases fall back to reading agy's transcript files, which is sensitive to agy's on-disk layout. Single-turn only (no multi-turn); defaults to the Gemini 3.1 Pro (High) model, falling back to Gemini 3.5 Flash (High) on a rate limit. Validated end-to-end against agy 1.0.6.

Installation

Run in your terminal:

# Project scope (current project only)
claude mcp add antigravity -- npx -y ask-antigravity-mcp

# User scope (all projects)
claude mcp add --scope user antigravity -- npx -y ask-antigravity-mcp

Or install as a plugin (adds slash commands like /multi-review, /brainstorm, /compare, plus reviewer subagents and the opt-in continuous codex-pair review hook):

/plugin marketplace add Lykhoyda/ask-llm
/plugin install ask-llm@ask-llm-plugins

Or install globally:

npm install -g ask-antigravity-mcp

Prerequisites

1. Node.js v20.0.0 or higher
2. Antigravity CLI (agy) installed and logged in once — run agy interactively to complete the Google Sign-In before using the MCP server

Tools

Tool	Purpose
ask-antigravity	Send a prompt to agy for a second opinion / code review. Optional includeDirs maps to agy --add-dir for monorepo context
get-usage-stats	Per-session token totals (in-memory)
ping	Connection test; also reports whether agy is installed

ask-antigravity returns both human-readable text and a structured AskResponse (provider, response, model, sessionId, usage) via MCP outputSchema.

How it works

agy ≥ 1.0.6 prints the response to stdout (gemini-cli #27466, the empty-stdout bug, is fixed there), so the executor uses a stdout-first source chain — structured JSON → plain stdout → transcript file. The transcript fallback reads the complete transcript_full.jsonl under ~/.gemini/antigravity-cli/brain/<id>/.system_generated/logs/. Calls are serialized in-process (concurrent agy runs race on shared state files). It runs with a read-only prompt preamble plus --dangerously-skip-permissions + --sandbox so agy never hangs on approval prompts.

Config

Env var	Default	Purpose
ASK_ANTIGRAVITY_TIMEOUT_MS	300000	Process timeout (5 minutes)
ASK_ANTIGRAVITY_SANDBOX	on	Set 0 to drop agy's --sandbox flag if it blocks --add-dir context reads
ASK_ANTIGRAVITY_MODEL	Gemini 3.1 Pro (High)	agy model passed via --model; on a rate limit the executor retries once on Gemini 3.5 Flash (High) (run agy models for the list — e.g. Claude Sonnet 4.6 (Thinking))

Limitations

• Experimental — the transcript fallback is sensitive to changes in agy's on-disk format.
• Single-turn — no multi-turn sessions (no capturable conversation id, antigravity-cli #7). Model selection is supported via --model (defaults to Gemini 3.1 Pro (High), with a Gemini 3.5 Flash (High) rate-limit fallback; see Config) — only the short -m flag hangs under -p.
• Interactive auth — requires an agy login, so it isn't suited to headless CI.

npm

• Package: ask-antigravity-mcp
• Binary: ask-antigravity-mcp